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P Bretlau

Publications and source records attributed to P Bretlau.

At least 19 recordsLinked to original sources
PubMed2001

Recognition of basic fuchsin prestained microfissures of intravital origin with fluorescence microscopy: validation of a shortcut.

For 70 years it has been suspected that not all microfissures in histological bone sections are artifacts, but that some are provoked in vivo through repetitive stress. The development of undecalcified bone techniques and of the bulk staining technique has established a method for demonstrating the existence of intravital cracks and enhanced the discrimination towards artifactual microfissures in the load-bearing skeleton. Recently the presence of intravital microfissures has also been ascertained in temporal bones by these techniques. Due to the fluorescent properties of basic fuchsin it is possible to use epifluorescence microscopy for analysis of microfissures after bulk staining with basic fuchsin. This provides a more steady microscopic background and a sharper delineation of surface level structures since no projection from lower levels interfere. Artifactual cracks, which in transmitted light microscopy may look like darkly stained intravital microfissures due to refraction phenomena, become invisible or colorless. Epifluorescence microscopy enhances the detection of both smaller and larger prestained intravital microfissures, and leaves only a minor part of the cracks without certain categorization. The epifluorescence mode of analysis has the further advantage of being independent of slice thickness, making feasible whole-specimen analysis by serial stepwise grinding. The present study shows that the number and the length of microfissures in the human otic capsule, counted and measured under the epifluorescence microscope, equals numerically the findings in light microscopy, enabling the routine use of this mode of analysis. This may prove to be of particular value in the research into the etiology and pathogenesis of otosclerosis as well as perilymphatic fistulae.

Adult↗
PubMed2001

Sensorineural hearing loss after vibration: an animal model for evaluating prevention and treatment of inner ear hearing loss.

Sensorineural hearing loss following a variety of acoustic trauma, including middle ear surgery, is well known. Current literature, which points to the deleterious influence of noise on the inner ear during surgery, has yet to assess the influence of vibration generated by the burr. The purpose of the study reported here was to establish an animal model that mimics drilling and can be used to explore methods of hearing loss prevention and treatment. A specially developed electromagnetic vibrator was calibrated and used in 59 guinea pigs to induce hearing loss. Both young and old guinea pigs were used. The bony external ear canal of guinea pigs were exposed to vibration or sound of varying duration and intensity. The vibration of the temporal bone and noise level in the middle ear were measured. Electrocochleography was recorded to evaluate the hearing loss. Among the young animals, 90% developed a significant threshold shift (TS > 20 dB), when vibrated with 250 Hz at an intensity of 6.2 m/s2 for 15 min. An average of 42 dB TS was observed. With 10 min exposure 63% showed a TS. The older animals vibrated for 5 min developed the same TS (mean TS 34 dB) as the young animals when vibrated for 10 min. The vibration-induced TS showed no recovery within 3 days of observation. In the contralateral ear 4 out of 5 animals showed TS > 20 dB. When exposed to sound levels exceeding the vibration-generated sound in the middle ear (119 dB at 250 Hz) only 2 out of II animals (18%) showed TS. The frequency of TS and level of TS were significantly greater in the vibrated animals than in sound-only exposed animals (p < 0.01). The degree of vibration-induced TS in the present animal model could be controlled by vibration intensity and duration. The older animals were more susceptible to vibration-induced inner-ear damage than younger animals. This model will be used in further studies to find methods for prevention and treatment of hearing loss during ear surgery.

Animals↗
PubMed2001

Demonstration of intravital microfissures in undecalcified plastic-embedded temporal bones with the prestaining technique.

Microfissures in the human otic capsule have been observed since the start of the century, but it was Otto Mayer, in 1930, who first realized that some of them were of intravital origin and not just processing artifacts. Since then, a small number of publications, based on decalcified temporal bones, have mostly confirmed his findings. With the introduction by Frost in the late 1950s of the undecalcified bone technique and the bulk staining technique for peripheral bones, a method was developed and refined for identifying even very small intravital microfissures (microdamage). Bulk staining of undecalcified otic capsules has not yet been used to verify the findings from the previous decalcified specimens. The present report presents our experience with the pertinent techniques, and suggests modifications and shortcuts pertinent to temporal bone research. Both large and tiny microfissures of intravital genesis are demonstrable within bulk-stained undecalcified human otic capsules. The importance of microfissures in the petrous bone in the causation of otosclerosis and perilymphatic leakage has long been discussed, and the present techniques may advance our understanding of these pathological conditions

Adult↗
PubMed2000

[Surgical treatment of otosclerosis with argon laser].

OBJECTIVES: Argon laser stapedotomy is a new modality for the treatment of otosclerosis. The first results obtained in Denmark are reported. MATERIALS AND METHODS: A retrospective follow-up study was undertaken to evaluate the results of argon laser stapedotomy which was introduced in 1991 at the department of Otolaryngology, Rigshospitalet, Copenhagen. The results are based on 85 consecutive primary stapedotomy operations with argon laser in 76 patients during the period January 1, 1991 to June 30, 1996. Mean follow-up was 16.6 months (6-60). RESULTS: The postoperative air-bone gap was closed within 10 dB or less in 83% of the operations and in 20 dB or less in 98%. The mean speech reception threshold (SRT) was 48 dB preoperatively. All patients had an improved SRT after the operation, with a mean value of 23 dB. At 4000 Hz and 8000 Hz, 89% and 65% of the patients had maintained or improved their hearing. No patient developed profound sensorineural hearing loss or anacusis after the operation. Only one patient developed symptoms of a temporary perilymphatic fistula. CONCLUSION: Argon laser stapedotomy is a safe technique. Its complications are fewer and not as serious as conventional methods. In addition, the achieved hearing results are better, and thus it is a good example of "minimal invasive high success surgery".

Adolescent↗
PubMed2000

Experience in qualitative and quantitative FDG PET in follow-up of patients with suspected recurrence from head and neck cancer.

We evaluated positron emission tomography (PET) with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) in the detection of recurrent head and neck cancer, and compared visual and quantitative interpretation of PET images for their accuracy in the identification of tumour recurrence. Sixty-two FDG PET studies were performed in 56 patients having a total of 81 lesions, which were clinically suspected for recurrent carcinoma of the head and neck. The PET images were interpreted visually, and tracer uptake was quantitated as the standardised uptake value adjusted to body weight (SUV). Sensitivity of visual interpretation of the PET images for the presence of malignancy ranged from 84 to 95%, and specificity from 84 to 93%, respectively, depending on the selected scheme for grading of the lesions. Malignant lesions accumulated significantly more FDG than the benign ones (the median SUVs were 6.8 and 3.3, respectively, P<0.001). However, there was a wide overlap of the FDG uptake values between these two groups. Hence, the highest accuracy of quantitative analysis in correct identification of tumour recurrence (75% at Receiver Operating Curve analysis) was inferior to that of visual analysis (89%). FDG PET is feasible for the detection of recurrent head and neck cancer. Although quantitation of FDG uptake using SUV shows significantly higher tracer concentrations for malignant than benign lesions, the wide overlap of individual SUVs between these two groups is a serious concern in diagnostic evaluation. Therefore, in clinical practice it may be preferable to identify the presence of tumour recurrence within this patient group by qualitative interpretation of the PET images.

Adult↗
PubMed2000

Predilection of otosclerotic foci related to the bone turnover in the otic capsule.

Using multiple fluorochrome tagging of eight mongrel dogs and a newly established methodology of measuring bone turnover (BTO) in the otic capsule, it has previously been demonstrated that BTO in the canine otic capsule is highly reduced close to the perilymphatic spaces (PLS) compared to the normal level of BTO in the periphery. Reanalysis of these data shows that this inhibition of BTO is far more pronounced around the cochlea and vestibule than around the semicircular canals. Similar tendencies are seen for the numerical density and mean label area of the bone remodelling units. With increasing distance to the PLS, these patterns are weakened, but still recognizable. In otosclerosis, foci of abnormal bone deposition are particularly frequent around the oval and round windows and in the cochlear capsule, i.e. where inhibition of bone remodelling is most prominent. A surpassing (or failure) of this pronounced inhibition must precede the tumultuous but delimited osteogenesis of otosclerosis. Otosclerosis may be a deviation of the normal BTO process in an osteometabolically abnormal site, perhaps initiated as an osteogenetic response to abnormal stress exposure.

Animals↗
PubMed2000

Database developed to record and evaluate computer aided endonasal surgery results.

Computer aided surgery has been used in the Department of Otolaryngology--Head & Neck Surgery, Rigshospitalet, Copenhagen since October 1998, and is now a regular supplement to conventional functional endonasal sinus surgery (FESS) and management of anterior skull base lesions. This technique was designed to enhance surgical precision and thoroughness and to reduce complications. Since this is a new technique, the clinical findings and surgical outcome are prospectively collected in a database. Results for conventional FESS are entered in the same database for comparison. The aim of this study is to present a standardized Danish database.

Databases as Topic↗
PubMed2000

Cystic hygroma of the head and neck--a long-term follow-up of 44 cases.

Cystic hygroma of the neck is a relatively rare congenital malformation usually diagnosed during the first years of infancy. Complete surgical extirpation may be impossible without sacrificing important neurovascular structures. This paper reports the long-term outcome of surgical treatment during a 35-year period. A follow-up examination of 44 patients (24 males and 20 females) treated in our departments during the last 35 years was performed. Median age at first operation was 1.5 years (0-28 years) The observation period ranged between 1 and 36 years, median 16.2 years. Indications for operation were space occupying lesion, haemorrhage, dysphagia, difficulties in pronunciation or breathing and infection or nerve lesions. Fifty percent of the patients revealed residual or recurrent hygroma at the time of follow-up. Forty-four percent suffered from impaired speech, food intake, breathing or swallowing. Thirty-six percent were cosmetically bothered, and only 11% reported reduced quality of life. A significant correlation was noted between the extension of the lesion and (i) the number of operations performed and (ii) the rate of recurrent or residual hygroma. The rate of residual or recurrent hygroma was statistically higher for the suprahyoid lesions compared with the infrahyoid lesions. The localization and extent of the lesion is related to the surgical outcome. Surgical intervention should be centralized and should be considered carefully. Neurovascular structures should not be damaged in an attempt to effect complete removal. The above-mentioned results lead to a search for a new therapeutic modality, and the authors have recently taken up the Japanese way of treating hygromas by intralesional injection of OK-432. The first two patients treated by this technique had total regression of the lesion, and the method seems to be promising as an alternative to surgery.

Adolescent↗
PubMed2000

Estimation of volume referent bone turnover in the otic capsule after sequential point labeling.

Using fluorochrome labeling and a newly validated method for bone turnover estimation, we determined absolute values for canine perilabyrinthine bone remodeling. The overall capsular bone turnover was found to be 2.1% per year, compared to 13.9% per year for the neighboring cranial bones and 7.4% per year for the humerus compacta. This gross 2.1% per year conceals a vast range, from 0.13% per year for the innermost perilymphatic zone, through a centrifugal increment toward 8% to 10% per year in the periphery. The underlying individual bone remodeling units exhibit a similar centrifugal pattern in numerical density and size. These findings indicate an inhibition of remodeling, seemingly emanating from the perilymphatic spaces, and affecting both the activation of osteoclasts and the extent of resorption by the osteoclasts. These values satisfactorily explain the preservation of such fetal remnants as the globuli ossei, the interglobular spaces, and the skein bone. In humans, local ineffective inhibition of bone resorption may play a role in the initiation of otosclerosis.

Animals↗
PubMed1999

Acute otitis media and sociomedical risk factors among unselected children in Greenland.

OBJECTIVE: To describe the sociomedical risk factors associated with episodes of acute otitis media (AOM), recurrent AOM (rAOM), and chronic otitis media (COM) in Greenlandic children and especially to point out children at high risk of rAOM (defined as > 5 AOM episodes since birth) and COM which are prevalent among Inuit children all over the Arctic. METHODS: The study design was cross-sectional and included 740 unselected children, 3, 4, 5, and 8-years-old, living in two major Greenlandic towns, Nuuk and Sisimiut. All children were otologically examined and the parents answered a questionnaire containing sociomedical variables including ethnicity, family history of OM, housing, insulation, crowding, daycare, passive cigarette smoking, breast feeding, type of diet, allergy, and chronic diseases. Historical data were cross-checked in medical records which also formed the basis for the drop-out analyses. Statistical analyses included frequency tests, calculation of odds ratio (OR), and multiple logistic regression. RESULTS: The attendance rate was 86%. Former episode of AOM was reported by 2/3 of the children, rAOM by 20%, and COM by 9%. The following variables were found significantly more often in children with AOM by simple frequency testing: Parental (OR = 1.83), sibling (OR = 1.62), and parental plus sibling (OR = 2.56) history of OM, crowding (OR = 5.55), long period of exclusive breast feeding ( > 4 months) (OR = 2.47), and recent acute disease (P = 0.034). The following variables were found significantly more often in children with rAOM or COM by simple frequency testing: Parental history of OM (OR = 1.60; OR = 2.11, respectively) and no recall of breast feeding (P = 0.005; P = 0.003, respectively). Also, COM was found significantly more often in children with two Greenlandic parents (OR = 3.07). A multiple logistic regression test denoted only parental history of OM (OR = 1.82) and long period of exclusive breast feeding (OR = 1.14) as significant predictors of AOM. CONCLUSIONS: Many of the risk factors usually associated with AOM could not be confirmed as risk factors in this survey. Parental history of OM and long period of exclusive breast feeding were the strongest factors associated with AOM in Greenlandic children and ethnicity was associated with COM. However, the study confirms that AOM is a multifactorial disease determined by a number of genetic and environmental factors.

Acute Disease↗
PubMed1999

The endolymphatic sac, a potential endocrine gland?

A previous investigation indicated that the chief cells of the endolymphatic sac produce an endogenous inhibitor of sodium re-absorption in the kidneys, which has tentatively been named "saccin". In this study, the ultrastructure of the endolymphatic sac and in particular the chief cells is described, demonstrating that this organ fulfils the morphological criteria of a potential endocrine gland. Accordingly, the chief cells are shown to exhibit all the organelles and characteristics of cells that simultaneously synthesize, secrete, absorb and digest proteins.

Animals↗
PubMed1999

Acute otitis media and age at onset among children in Greenland.

This survey examines the age at onset of acute otitis media (AOM) in 591 unselected Greenlandic children aged 3, 4, 5 and 8 years from the two largest towns in Greenland. The attendance rate was 86%. Parental information about episodes of AOM was cross-checked in medical records, which were available for 95% of the children. AOM was defined as episodes with earache, otorrhoea or previous treatment for AOM, with written otoscopic evidence of AOM resulting in treatment with weak analgetics or antibiotics. Recurrent AOM (rAOM) was defined as > or = 5 AOM episodes since birth. In total, 66% of the children had experienced AOM at least once. Of all children, 40% had AOM during the first year of life. Median age of the first episode was 10 months (range: 1-84 months), and there was no sex difference. Children between 7 and 12 months of age were at highest risk of AOM. Children with rAOM had their first AOM episode at a significantly younger age than children with < 5 AOM episodes (median: 7 months, range: 2-48 months). In addition, 83% of children with rAOM had their first AOM episode before 12 months of age compared with 53% of children with < 5 episodes (p < 0.0001). The relative risk of rAOM was eight times greater if the first episode of AOM occurred before six months of age compared to more than 24 months of age. Thirty-five percent of children with rAOM had chronic otitis media as well, compared to only 4% of children with < 5 AOM episodes. We conclude that early onset of AOM (before one year of age) occurs frequently in Greenlandic children compared to others, and a high proportion of these children develop rAOM.

Acute Disease↗
PubMed1998

Volume-referent bone turnover estimated from the interlabel area fraction after sequential labeling.

In the compact bony otic capsule remodeling is low, and bone remodeling units are distributed centrifugally in relation to inner ear tissues and spaces. Fluorochrome-labeled bone remodeling units are scarce, abortive, and tortuous with no uniform direction of movement. This study presents a method for the estimation of volume-referent bone turnover based on measurements of the fractional area between labels after sequential labeling with osteofluorochromes. The applicability of this method is tested against a classical quantification method in undecalcified cortical specimens from the canine humerus, where both methods can be used. The estimate of bone turnover derived from the new sequential labeling in eight dogs is 7.4% (SEM 2.1%) per year and the classic estimate derived from calculations of the formative osteonal area and the formative period yields 6.9% (SEM 2.1%) per year. Agreement is sufficient to justify future measurements of absolute bone turnover in sequentially labeled perilabyrinthine bone.

Animals↗
PubMed1998

An aggressive and invasive growth of juvenile papillomas involving the total respiratory tract.

A malignant course of juvenile laryngeal papillomatosis has rarely been reported. In the present case the patient had had laryngeal papillomas since the age of three years. The papillomas gradually spread to the entire respiratory system, and during 30 years the patient was operated on more than 80 times. At present an invasive tumour spreading from the tongue into the parapharyngeal space, extending to the cranial base, has been demonstrated by magnetic resonance imaging (MRI). Intralesional therapy with Cidofovir, a promising antiviral drug against human papillomavirus (HPV) infection, was started with some clinical effect, although only on the superficial tumour growth. Histology of removed tumour tissue has demonstrated a mixture of exophytic and inverted growth pattern, and has mainly been interpreted as benign, in spite of a focally high mitotic index and an intermittent lack of maturation in the epithelium. In the most recent biopsies a verrucous carcinoma has been diagnosed. Expression of p53 was noted to increase in papillomas with time. All samples have been shown to harbour HPV 11, but no other HPV types.

Adult↗
PubMed1998

Respiratory tract infections in Greenlandic children: a prospective cohort study.

Respiratory tract infections in children, measured in terms of both morbidity and mortality, represent a major health problem in Greenland. In particular, otitis media is highly prevalent, and is characterized by early onset and a high degree of chronicity. There is, however, little knowledge about the epidemiology of respiratory tract infections in Greenland. In the spring of 1996, a prospective study of such infections in infants and children was initiated in Sisimiut, West Greenland. The main objectives of the study are to describe the epidemiology of respiratory tract infections in children under four years of age, to estimate the impact of these diseases on short- and long-term morbidity, and to identify risk factors for transmission and clinical severity. An open cohort of children in Sisimiut will be formed, including all resident children below three years of age at the beginning of the study, as well as all children born in the following two-year period: in total approximately 600 children. During two years, these children will be followed closely, including registration of episodes of respiratory tract infections. Furthermore, growth will be measured and microbiological samples obtained.

Child, Preschool↗
PubMed1996

Prevalence of otitis media in a survey of 591 unselected Greenlandic children.

In an unselected survey in two Greenlandic towns, 591 children were examined to study the prevalence of otitis media (OM). The attendance rate in Nuuk was 80%, while 93% participated in Sisimiut. The children were three-, four-, five- and eight-years-old and represented 18% of children in these age groups in all Greenland. In total, 51.7% in Nuuk and 54.1% in Sisimiut presented pathologic middle ear affections ranging from slight to severe. The prevalence rates of chronic OM (COM) were 6.8% in Nuuk and 11.7% in Sisimiut (P = 0.055) but without significant age or sex difference. The acute OM point prevalence rate was between 1.5% and 0.4%. The prevalence rate of middle ear effusion (MEE) was between 23.0% and 28.2%. Secretory OM was significantly more prevalent in the younger age groups. The odds ratio of having COM was significantly higher in children with two Greenlandic born parents (3.07) than in children with only one Greenlandic born parent. A follow-up study after one year in Sisimiut revealed unchanged or aggravated middle ear disease in 56.8% of 82 children with middle ear pathology at the primary survey. Thus, OM persists as a major health problem among Greenlandic children, although the general socio-economic and medical conditions have improved during the last decades. Proposals are provided for increased otologic efforts.

Acute Disease↗