Poul Bretlau

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.

Epidermal growth factor receptor expression on oral mucosa dysplastic epithelia and squamous cell carcinomas.

SummaryThe expression of the receptor for epidermal growth factor (EGF) has been determined on oral squamous cell carcinomas. Immunoreactive receptor was localized using a monoclonal anti-EGF-receptor antibody which reacts with sequences in the external domain of the receptor. Frozen sections were studied from 40 patients with squamous cell carcinomas. In 16 sections from the patients with the squamous cell carcinomas, normal differentiated oral mucosa was included and in 7 of these the patients had received preoperative radiotherapy. Sections from 6 other patients with squamous cell carcinoma contained dysplastic epithelia. EGF-receptor-positive cells were present in the basal cell layer on normal differentiated oral mucosa. In sections from patients receiving preoperative radiotherapy the EGF-receptor-positive cells were also found in the spinous cells. In dysplastic epithelia nearly all cells stained for the receptor. The distribution and staining intensity of the EGF receptor varied in the oral squamous cell carcinomas, 36 were positive. The staining pattern in the carcinomas obtained from patients receiving preoperative radiotherapy was not altered qualitatively. Nearly all poorly differentiated cells were stained, but when the tumor was moderately to well differentiated a reduction in the extent of staining in certain areas was seen, paralleling the findings observed in the differentiated upper layers of the normal oral mucosa. This was most pronounced for the epithelial pearls, where the EGF-receptor-positive cells were localized to the undifferentiated cells in the periphery. The results of the present investigation confirm the presence of the EGF receptor on undifferentiated cells, with the extent of the staining reaction on oral squamous cell carcinomas varying inversely with cellular differentiation.

Familial clusters of nasopharyngeal carcinoma and salivary gland carcinomas in greenland natives

Background. Nasopharyngeal carcinoma (NPC) and anaplastic salivary gland carcinoma (SGC), both associated with Epstein‐Barr virus (EBV), are common among Inuit from Greenland, Canada, and Alaska. Because immigrant studies have shown that factors acting early in life are important for the development of NPC, the authors interviewed new patients in Greenland with either NPC or SGC about their lifestyles during childhood and additional cases in their families.

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.

In Vivo Visualization of Endolymphatic Hydrops in Guinea Pigs: Magnetic Resonance Imaging Evaluation at 4.7 Tesla

In order to find out whether it is possible to visualize experimental endolymphatic hydrops in the cochlea with magnetic resonance imaging (MRI) at 4.7 T, we used 11 guinea pigs. Five normal guinea pigs were used as controls. Early manifestation of endolymphatic hydrops was evaluated in endolymphatic sac (ES)–intact animals (n = 6), and advanced manifestation in ES-damaged animals (n = 5) by means of MRI with gadolinium-diethylenetriaminepentaacetate-bismethylamide (Gd-DTPA-BMA) contrast agent. Hearing was tested with electrocochleography. The surface area of 3 partitions of the cochlea was used to quantify endolymphatic hydrops. The fine structure of the 3 partitions of the cochlea was visualized with MRI in all animals, as Gd-DTPA-BMA appeared mainly in the scala tympani and scala vestibuli. As early as 5 days after endolymphatic sac surgery, endolymphatic hydrops started to appear as visualized by MRI and also verified with histology. Severe damage to the inner ear barrier with Gd-DTPA-BMA leakage into the scala media was detected with MRI in 1 ES-damaged animal that had a 60-dB hearing loss. To conclude, endolymphatic hydrops can be visualized with high-resolution MRI by means of Gd-DTPA-BMA, and it is possible to quantify the extent of endolymphatic hydrops. Damage to the inner ear barrier or possible rupture of membranes can be shown with the assistance of Gd-DTPA-BMA.

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.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 11 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.

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.

In Vivo Observation of Dynamic Perilymph Formation Using 4.7 T MRI with Gadolinium as a Tracer

Objective—To investigate the pharmacokinetics of gadolinium in the perilymphatic fluid spaces of the cochlea in vivo using high-resolution MRI to obtain information concerning perilymph formation. Material and Methods—A Bruker Biospec Avance 47/40 experimental MRI system with a magnetic field strength of 4.7 T was used. Anesthetized pigmented guinea pigs were injected with the contrast agent Gd-diethylenetriaminepentaacetic acid-bismethylamide and placed in the magnet. The signal intensity of Gd in the tissues was used as a biomarker for dynamic changes in the perilymphatic fluid. Results—The most rapid uptake of Gd in the perilymphatic fluid spaces occurred in the lower part of the modiolus, followed by the second turn of the scala tympani. Within the scala tympani, the distribution of Gd in the basal turn was significantly lower than that in the other turns. Destruction of the cochlear aqueduct was followed by an increase in Gd uptake in the perilymph instead of a reduction. Conclusions—These findings offer further evidence that the pervasive perilymphatic fluid derives from the cochlear blood supply via the cochlear glomeruli, which are in close proximity to the scala tympani within the modiolus, and the capillary in the spiral ligament. Cerebrospinal fluid communicates with perilymph via the cochlear aqueduct but is not the main source of perilymph. These findings are of relevance to the treatment of inner ear diseases, as well as to our understanding of the flow and source of perilymphatic fluid.

Histiocytic activity in the otosclerotic bone.

ZusammenfassungDie vielkernigen Riesenzellen, die Osteoclasten, werden im allgemeinen für die Knochenresorption im Otoskleroseherd allein verantwortlich gemacht. Nach unserer Meinung können aber die Osteoclasten nicht allein den Knochenabbau der verschiedenen lytischen Phasen des Otoskleroseherdes im langen Ablauf seiner Entwicklung erklären.Unsere Untersuchungen haben mononucleäre, lysosomenreiche Zellen aufgedeckt, die wir für Histiocyten halten.Nach ihrer Lokalisation und Morphologic wie auch nach ihrem Enzymgehalt spielen diese Zellen vermutlich eine entscheidende Rolle im otosklerotischen Resorptionsprozeß. Möglicherweise bilden sich die Osteoclasten durch Verschmelzung von Histiocyten.Die vorliegenden Befunde bestätigen unsere frühere Theorie, daß die Otosklerose eine Enzymerkrankung ist, wobei die destruktive Phase durch die Wirkung der Hydrolasen in den „Lysosomen” genannten Cytoplasmakörpern erklärt werden könnte.SummaryThe multinuclear giant cells, the osteoclasts, are generally held solely responsible for the resorption of bone in the otosclerotic focus. Our light microscopic and electron microscopic studies of 369 otosclerotic foci have elucidated the scarcity of osteoclasts. In our opinion, the osteoclasts cannot solely explain the breakdown of bone in the various lytic phases passed by an otosclerotic focus in the long course of its evolution. Our investigations disclosed a mononuclear cell, rich in lysosomes, which we interpret as a histiocyte. Judging by its localization and morphology as well as its enzymatic contents, this histiocyte presumably plays a decisive role in the otosclerotic process of resorption. Possibly osteoclasts form by fusion of histiocytes.The present findings confirm our previous theory that otosclerotis is an enzymatic disease whose destructive phase might be explained by the action of the hydrolases found in the dense cytoplasmic bodies called lysosomes.

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.