Biomedical subjects

Frans W J Albers

Publications and source records attributed to Frans W J Albers.

At least 19 recordsLinked to original sources

PubMed2006

Differences in aerodynamic characteristics of new and dysfunctional Provox 2 voice prostheses in vivo.

Tracheoesophageal voice prostheses need to be replaced due to increased airflow resistance or retrograde leakage of fluid into the trachea as a consequence of biofilm formation. Previous in vitro studies show a change of aerodynamic features of biofilm covered voice prostheses after removal of the prostheses out of the patient. To assess these changes in an in situ situation, aerodynamic characteristics were measured within 45 patients at the beginning and at the end of the wearing process of the Provox 2 voice prosthesis. As a consequence, the influence of biofilm formation on aerodynamic characteristics can be evaluated. In the majority of cases, leakage through the prosthesis was the reason for replacement. No differences were found in the total flow, volume range and intratracheal pressure (ITP) of the voice prostheses measured. The airflow resistance of biofilm covered prostheses was significantly reduced compared to new clean prostheses. However, no correlation was found between the extent of biofilm and the different aerodynamic features measured. Biofilm formation on the Provox 2 is responsible for both reduction in airflow resistance and leakage through the prosthesis by deterioration of the silicone rubber material.

Air Pressure↗

PubMed2005

Evaluation of the relation between audiometric and psychometric measures of hearing after tympanoplasty.

The objective of this prospective study was to evaluate the relation between audiometric and psychometric measures after tympanoplasty from the perspective of preoperative selection of patients and postoperative assessment of the results of reconstructive middle ear surgery. Hearing (dis)ability was measured by means of pure-tone audiometry and a validated self-assessment questionnaire: the (modified) Amsterdam Inventory of Auditory Disability and Handicap (m)AIAD. Average hearing thresholds and (m)AIAD scores were evaluated for 80 patients, pre- and 12 months postoperatively. The average improvement of the air conduction threshold in the operated ear was 5.4 (+/-14.3) dB; the average improvement in the (m)AIAD score was 2.9 points (+/-12.1). Although not very strong, the audiometric improvement and increase in (m)AIAD score are significantly related. After the calculation of postoperatively measured mean scores on the (m)AIAD for different 10-dB intervals of postoperative hearing loss averaged over both ears, an interesting relation between the (m)AIAD score and hearing losses emerges. The (m)AIAD score is almost independent of hearing loss for postoperative hearing levels between 25 and 40 dB. Residual hearing loss has to become less than 25 dB before a smaller hearing loss corresponds with a higher (better) (m)AIAD score. For losses larger than 40 dB the (m)AIAD score clearly decreases with increasing hearing loss. Finally, even small residual hearing losses lead, on average, to (m)AIAD scores that are substantially lower than the score for normally hearing subjects. In general, the patient benefit seems related to the magnitude of improvement in the air-conduction thresholds, rather than to the achievement of a certain threshold level. In addition, even small residual hearing losses (less than 25 dB HL) still lead, on average, to (m)AIAD scores that are substantially lower than the scores for normally hearing subjects.

Adolescent↗

PubMed2005

Effect of dairy products on the lifetime of Provox2 voice prostheses in vitro and in vivo.

BACKGROUND: Reduction of biofilm formation on tracheoesophageal voice prostheses by certain dairy products might extend their clinical lifetime. The purpose of this study was to determine the influence of certain dairy products on voice prosthetic biofilms and lifetimes in vitro and in vivo. METHODS: The in vitro results were accomplished using an artificial throat. The lifetimes of Provox2 prostheses were evaluated in a patient group that daily consumed the evaluated products. RESULTS: Buttermilk and Yakult Light fermented milk decreased the amount of bacteria on voice prostheses but stimulated yeast prevalence in vitro. Concurrently, lifetimes of voice prostheses in patients consuming buttermilk were not significantly different, whereas patients consuming Yakult Light fermented milk drink had a significantly (p < .01) increased prosthesis lifetime by a factor of 3.76. CONCLUSION: Yakult Light fermented milk drink reduced biofilm formation on Provox2 prostheses in vitro and in vivo and significantly increased prosthesis lifetime. In vivo, no significant effects were observed for patients consuming buttermilk.

Aged↗

PubMed2005

In vitro leakage susceptibility of tracheoesophageal shunt prostheses in the absence and presence of a biofilm.

Although leakage through a tracheoesophageal shunt prosthesis is the main cause of prosthesis failure in a laryngectomy patient, this has never been the subject of in vitro evaluation. The aim of this study was to compare three commercially available voice prostheses by comparison of their in vitro leakage patterns, in absence or presence of a biofilm. To compare in vitro leakage patterns, a model comprised of an artificial throat equipped with a single prosthesis coupled to a water reservoir was developed. By varying the height of the water reservoir, different pressures on the voice prosthesis can be obtained. Both in absence and presence of a biofilm, the Blom Singer voice prosthesis demonstrated the lowest leakage, followed by Groningen Low Resistance. The Provox2 showed significantly the most leakage, however, in presence of a biofilm the leakage of the Provox2 significantly decreased. Regular airflow during biofilm formation significantly increased leakage through the Provox2. Out of 746 clinical replacements, Provox2 showed 76% and Groningen Low Resistance 57% replacements due to leakage. The model used in this study showed significant differences in leakage of the three types of voice prostheses used. Leakage occurred more readily through Provox2 than through Groningen Low Resistance and Blom Singer prostheses, which is in line with clinical observations and enforces the model.

Area Under Curve↗

PubMed2005

Analysis of cortisol and other stress-related hormones in patients with Ménière's disease.

OBJECTIVE: To evaluate cortisol and catecholamine levels in patients with Ménière's disease. STUDY DESIGN: Prospective, controlled study. SETTING: Tertiary referral center. PATIENTS: Thirty patients with Ménière's disease and 18 healthy controls. MAIN OUTCOME MEASURES: Serum and saliva cortisol, serum cortisol after the dexamethasone suppression test, urine free cortisol, and urine catecholamines. RESULTS: The serum and saliva cortisol levels were higher in Ménière's patients compared with their control group: 440 +/- 127 (n = 28) versus 366 +/- 90 (nmol/L) (n = 18) and 17.2 +/- 6.1 (n = 18) versus 11.6 +/- 4.6 (nmol/L) (n = 9), respectively. Both differences were significant (p < 0.05). There were no dissimilarities in urine cortisol or urine catecholamines for either group. Twenty-eight Ménière's patients were divided into two subgroups, namely, high- and low-cortisol groups, using a serum cortisol level cutoff point of 465 nmol/L (median). The total Ménière's disease time and the duration of tinnitus tended to be longer in the high-cortisol group (p = 0.07, two-tailed). The total Ménière's disease time was 13.5 +/- 9.9 years in the high-cortisol group and 7.1 +/- 7.4 years in the low-cortisol group (n = 14 for both). The subgroups were matched for age, gender, and unilaterally or bilaterally affected ears. CONCLUSION: Patients with Ménière's disease have higher serum cortisol levels. It is suggested that these higher cortisol levels are rather the result than the cause of this chronic disease, because patients affected longer seem to have higher cortisol levels. The exact impact of these higher cortisol levels on the inner ear and endolymph homeostasis is yet unknown.

Adult↗

PubMed2004

Evaluation of cochlear function in an acute endolymphatic hydrops model in the guinea pig by measuring low-level DPOAEs.

During and after microinjection of artificial endolymph into scala media of the guinea pig, the 2f1- f2 -DPOAE at 4.5 kHz generated by low-level primaries was recorded. Reproducible changes were measured when 1.1 microl of artificial endolymph was injected at a rate of 1.65 nl/s (1.53-1.83). This volume corresponds with an acute endolymphatic hydrops of 23%. After the onset of injection the inner ear pressure immediately increased to a mean higher level of 22 Pa, whereas the 2f1- f2 -amplitude and -phase did not change for about 1 min. Thereafter, the amplitude decreased 2.6 dB (+/- 0.7) on average and slowly regained almost its initial value, with recovery frequently starting within the period of injection. In an attempt to explain the observed changes in 2f1- f2 -amplitude the basilar membrane displacement towards scala tympani at the 2f1- f2 generation site is estimated to be 19 nm for a 1.1 microl increase of endolymph volume. A small deflection of the outer hair cell stereocilia and as a consequence a change in cell conductance may explain the 2f1- f2 -amplitude changes. However, the precise mechanism of cochlear function change caused by endolymph volume increase (hydrops) remains to be elucidated.

Acute Disease↗

PubMed2004

Direct measurement flow resistance of cochlear aqueduct in guinea pigs.

OBJECTIVE: The cochlear aqueduct connects the scala tympani to the subarachnoid space and is the main pressure equalization canal for the inner ear. Increases in inner ear volume and pressure are thought to cause clinical symptoms such as vertigo, tinnitus and fluctuating hearing loss. In this study the flow resistance of the cochlear aqueduct was determined and its relation with inner ear pressure was studied. MATERIAL AND METHODS: Inner ear pressure was measured in the scala tympani through the round window using a micropipette. Through a second micropipette, artificial perilymph was infused into, or withdrawn from, the scala tympani at various constant rates. From the infusion rate and the change in perilymphatic pressure during infusion the flow resistance of the cochlear aqueduct was calculated. RESULTS: The flow resistance was found not to be constant but to depend on the position of the round window membrane and possibly on the magnitude and direction of fluid flow through the aqueduct. Measured flow resistance values were in the range 11-45 Pa s/nl. For very small flow values the flow resistance averaged over 6 animals was 21 Pa s/nl. CONCLUSIONS: The flow resistance of the cochlear aqueduct is not a constant value. The cochlear aqueduct is a canal with dynamic properties and may play a role in the complicated process of inner ear pressure regulation.

Animals↗

PubMed2004

Prevention of biofilm formation by dairy products and N-acetylcysteine on voice prostheses in an artificial throat.

OBJECTIVE: To evaluate the preventive effect of buttermilk, Yakult Light fermented milk drink and N-acetylcysteine on biofilm formation on voice prostheses in vitro. MATERIAL AND METHODS: Groningen button and Provox 2 voice prostheses were inoculated with a mixture of bacteria and yeasts isolated from previously explanted Groningen button voice prostheses. After 5 h, separate throats were flushed with buttermilk, Yakult Light fermented milk drink, N-acetylcysteine or phosphate-buffered saline, which served as a control. After 7 days, the microflora on each voice prosthesis was determined. RESULTS: On Groningen button voice prostheses, buttermilk, Yakult Light fermented milk drink and N-acetylcysteine all reduced the amount of both bacteria and yeasts. On Provox 2 voice prostheses, buttermilk, Yakult Light fermented milk drink and N-acetylcysteine reduced the amount of bacteria but, conversely, increased the amount of yeasts. CONCLUSION: These in vitro experiments demonstrate that biofilm formation on voice prostheses is reduced in an artificial throat by the use of buttermilk, Yakult Light fermented milk drink and N-acetylcysteine. However, the structural differences between the type of voice prostheses may influence the ultimate effects.

Acetylcysteine↗

PubMed2004

Functional and anatomic alterations in the gentamicin-damaged vestibular system in the guinea pig.

HYPOTHESIS: The purpose of this study was to investigate the expected functional and morphologic effect of gentamicin on the vestibular system simultaneously by measurement of vestibular evoked potentials and electron microscopic evaluation. BACKGROUND: Vestibular short-latency evoked potentials to linear acceleration have been shown to be a useful parameter of vestibular function. In gentamicin-treated animals, the morphologic damage has been well documented, although this has seldom been quantified. METHODS: Fifteen guinea pigs were divided into three equal groups. Two groups received different dosages of intramuscular gentamicin for 3 weeks; the third group was the control group. Vestibular short-latency evoked potentials to linear acceleration pulses were measured. After the last gentamicin dose, the utricles were prepared for scanning and transmission electron microscopy. On scanning electron microscopy photographs, the surface area damage ratio of the utricles, a simple method of quantifying gross morphologic damage, was calculated. RESULTS: The vestibular short-latency evoked potential of gentamicin-treated guinea pigs showed a slow-developing, damaging, dose-response effect on the function of the vestibular system (p = 0.01). Scanning electron microscopy and transmission electron microscopy showed severe morphologic damage in the sensory hair cells of the utricle. The surface area damage ratio showed a dose-response relationship (p = 0.01). CONCLUSION: Functional and anatomic alterations in the gentamicin-damaged vestibular system in the guinea pig are related.

Animals↗

PubMed2004

Prediction of survival and therapy outcome with 11C-tyrosine PET in patients with laryngeal carcinoma.

UNLABELLED: Choosing the optimal treatment for an individual with squamous cell carcinoma of the head and neck is a difficult challenge because of the unpredictable clinical behavior of this malignancy. A reliable method for assessing the clinical behavior and predicting the radiocurability of tumors would assist in the therapy strategy and prognosis. This study evaluated whether quantitative PET using l-[1-(11)C]-tyrosine (TYR) has predictive value for survival and therapy outcome in patients with primary squamous cell carcinoma of the larynx. METHODS: Thirty-four patients with histologically confirmed laryngeal carcinomas underwent dynamic (11)C-TYR PET before receiving definitive therapy. Various methods for quantification of tumor activity were used: assessment of protein synthesis rate (PSR), calculation of standardized uptake value, and estimation of tumor-to-nontumor ratio. Treatment consisted of radiotherapy (n = 20) or surgery (n = 14). The median follow-up was 40 mo. RESULTS: All malignancies were identified correctly, with no false-negative results. Cumulative survival was compared between patients with tumor PSR equal to or higher than the median (2.0 nmol/mL/min) and those with tumor PSR lower than the median and was found not to be significantly different (P = 0.07). When the radiotherapy group was evaluated separately, the difference in survival was significant (P = 0.03; 5-y survival, 30% vs. 73%) and high (11)C-TYR uptake correlated with poor prognosis. In multivariate analysis, PSR was an independent predictor for survival. Because differences (P = 0.08) between patients with and patients without recurrence were not significant, no predictive value of PSR for disease recurrence could be demonstrated. CONCLUSION: Prediction of survival of patients undergoing radiotherapy for laryngeal squamous cell carcinoma is feasible primarily by using (11)C-TYR PET to quantify activity before treatment.

Adult↗

PubMed2003

Therapy evaluation of laryngeal carcinomas by tyrosine-pet.

INTRODUCTION: One of the major problems in head and neck oncology is determination of tumor status after radiotherapy. Physical examination and conventional imaging by CT and MRI do not always accurately differentiate between residual or recurrent tumor and posttreatment inflammation, fibrosis, edema, or scarring. The feasibility of positron emission tomography (PET) with L-[1-(11)C]-tyrosine (TYR) for therapy evaluation of laryngeal squamous cell carcinomas by identification of residual or recurrent disease after radiotherapy was investigated. PATIENTS AND METHODS: Nineteen patients with laryngeal carcinomas had standard workups with endoscopy and conventional imaging. All subjects underwent a TYR PET scan (PET1) before definitive treatment. For determination of tumor status, a second TYR PET scan (PET2) was performed 3 months after radiotherapy. At the time of scanning, seven patients were clinically suspected of having residual disease, and in these cases, additional CT imaging and biopsies during endoscopy were performed. During the minimal follow-up period of 29 months, six patients had clinical suspicion of recurrent disease. In these six cases, a third TYR PET (PET3), CT imaging, and biopsy were performed. RESULTS: All pretreatment tumors were depicted by TYR PET (PET1). Three months after radiotherapy, sensitivity and specificity of TYR PET (PET2) for discrimination between residual tumor and benign posttreatment tissue changes were both 100%, and for CT, 50% and 67%, respectively. For detection of recurrent tumor during follow-up, sensitivity and specificity of TYR PET (PET3) were also 100%, and CT, 75% and 50%, respectively. CONCLUSIONS: Dynamic TYR PET is an accurate imaging modality for therapy evaluation in detection of residual and recurrent disease with higher sensitivity (100%) and specificity (100%) for discrimination of tumor status by TYR PET compared with conventional imaging.

Aged↗

PubMed2003

Cochlear aqueduct flow resistance is not constant during evoked inner ear pressure change in the guinea pig.

Inner ear fluid pressure was measured during 6.25 mHz square wave middle ear pressure manipulation, with a perforated tympanic membrane. After a negative-going middle ear pressure change the calculated flow resistance of the inner ear pressure release routes (mainly the cochlear aqueduct) was approximately constant, with a value of 12 Pa s/nl (averaged over two ears), when values for the inner ear window compliance are taken from the literature. After a positive-going middle ear pressure change the calculated flow resistance changed with round window position and with the pressure difference across the cochlear aqueduct. It reached an average maximum value of 114 Pa s/nl. The change of flow resistance during inner ear pressure variation can be explained by a permeability change of the cochlear aqueduct, caused by a change of structures filling the aqueduct and its entrance in scala tympani.

Animals↗

PubMed2003

Quantification of audiogram fine-structure as a function of hearing threshold.

We investigated the amount of fine-structure in the audiograms of patients with Menière's disease. Both ears (often an affected and an unaffected ear) were investigated. Data are presented from 39 ears of 21 patients with hearing thresholds varying from about 0 to 70 dB HL. The fine-structure was measured in the frequency range from 500 to 3500 Hz; this agrees with a part of the basilar membrane from 10 to 22.5 mm from the apex. The fine-structure was characterized by means of the number of peaks N(p) and the sum S(p) of the heights of all the peaks in an audiogram. From these quantities, we also determined average peak height H(p). We found a negative correlation between hearing loss and strength of fine-structure, i.e. the higher the thresholds the smaller N(p) and S(p) as well as H(p). Also N(p) and H(p) were correlated, i.e. the more peaks the higher the average peak height. The summated peak height S(p)=N(p)H(p) showed a strong dependence on the hearing loss. In cases of strong fine-structure, S(p) reached values around 200 dB.

Adult↗

PubMed2003

Reliability and validity of the (modified) Amsterdam Inventory for Auditory Disability and Handicap.

This study investigated the psychometric adequacy of the (modified) Amsterdam Inventory for Auditory Disability and Handicap ((m)AIAD). The original version of the AIAD was developed by Kramer et al in 1995. Special emphasis was placed on the statistical aspects of the scores, because these properties place limits on the clinical utility of the instrument. The AIAD is a self-assessment questionnaire that consists of 30 questions covering all the relevant factors of disability in individual hearing functioning in daily life. This paper reports data from 94 subjects, aged 17-65 years, with different hearing abilities, who completed a modified version of the AIAD and the Hearing Disability Questionnaire (HDQ), on two occasions 1 month apart. The psychometric adequacy of the AIAD was determined by measuring its reliability and validity. Factor analysis was performed, and the reliability was tested by measuring internal consistency, split-half correlation, and test-retest reproducibility. The validity was tested by measuring construct and criterion validity. The results showed that the reliability of the (m)AIAD was highly satisfactory, with good internal consistency, high split-half correlations, and high test-retest correlations. Construct validity showed a high correlation between scores on the (m)AIAD and scores on the HDQ. Criterion validity showed a moderate but significant correlation between scores on the (m)AIAD and hearing thresholds in dB HL.

Adolescent↗

PubMed2003

L-1-11C-tyrosine PET in patients with laryngeal carcinomas: comparison of standardized uptake value and protein synthesis rate.

UNLABELLED: PET with L-1-(11)C-tyrosine (TYR) can measure and quantify increased protein synthesis in tumor tissue in vivo. For quantification of the protein synthesis rate (PSR), arterial cannulation with repeated blood sampling to obtain the plasma input function and a dynamic TYR PET study to calculate a time-activity curve are necessary. In most PET studies the standardized uptake value (SUV) method is used to quantify tumor activity. The SUV can be calculated without repeated arterial blood sampling and prolonged scanning time, as required for determination of the PSR. The relationship between PSR and SUV is largely unknown and different factors can cause wide variability in the SUV. Therefore, the comparison of the absolute quantification method (PSR) with the SUV method is obligatory to determine the possible use of noninvasive PET in head and neck oncology. METHODS: Twenty-four patients with proven squamous cell carcinomas of the larynx (T1-T4) were studied using dynamic TYR PET. The PSRs of tumor and nontumor (background) regions were determined. Four different methods were used to calculate the SUV: uncorrected SUV (SUV(BW)); and SUVs corrected for body surface area (SUV(BSA)), for lean body mass (SUV(LBM)), and for the Quetelet index (SUV(QI)). Correlations between PSR values and SUVs were calculated. RESULTS: The PSR of all tumors was significantly higher (P < 0.001) than the PSR of nontumor tissue. The correlations of SUV(BW), SUV(BSA), SUV(LBM), and SUV(QI) with the quantitative values of the PSR were high (r = 0.84-0.90). The best correlation was observed with the SUV based on the LBM (SUV(LBM)). CONCLUSION: High correlation between the quantitative values (PSR) and the SUVs offers the possibility to use noninvasive TYR PET for detection and reliable quantification of primary head and neck tumors.

Aged↗

PubMed2002

Carbon-11 tyrosine PET for visualization and protein synthesis rate assessment of laryngeal and hypopharyngeal carcinomas.

Accurate assessment of tumour extent and lymph node involvement in squamous cell carcinomas of the head and neck region is essential for therapy planning. Unfortunately, conventional diagnostic examination and imaging techniques, which monitor tumours on the basis of anatomical parameters, have drawbacks in clinical practice. The aim of this study was to investigate the feasibility of L-[1-(11)C]-tyrosine (TYR) positron emission tomography (PET) for visualisation of squamous cell carcinoma of the larynx and hypopharynx and quantification of tumour activity by assessment of protein synthesis rate (PSR). Dynamic TYR PET was performed on 31 patients with T1-T4 laryngeal or hypopharyngeal carcinoma before therapy. Plasma activity of TYR, (11)CO(2) and (11)C-protein levels were measured, and PSRs were calculated for primary malignancies. All 31 laryngeal and hypopharyngeal tumours were visualised as a hotspot (sensitivity 100%). The median PSR of the tumours (2.06 nmol ml(-1) min(-1); range 0.72-6.96) was significantly higher ( P<0.001) than that of non-tumour (background) tissue (0.51 nmol ml(-1) min(-1); range 0.22-0.89). L-[1-(11)C]-Tyrosine PET appears to be a potential method for visualisation of primary laryngeal and hypopharyngeal tumours. In vivo quantification of tumour activity by assessment of PSR is possible and may have a future role in the therapy planning and therapy evaluation of laryngeal and hypopharyngeal tumours.

Adult↗

PubMed2002

Cochlear ultrastructure in two-phase endolymphatic hydrops in the guinea-pig.

Endolymphatic hydrops continues to be considered as a pathological factor in the etiology of Meniere's disease. We have developed the two-phase endolymphatic hydrops model, which seems to represent a functional model combining multiple etiologies, and which may resemble the fluctuating characteristics of Meniere's disease. A transmission electron microscopic study was performed on the endolymphatic sacs of four groups of guinea-pig cochleas: (1) controls, (2) non-operated, aldosterone-treated cochleas, (3) operated (dissection of the endolymphatic sac) cochleas, (4) operated and aldosterone-treated cochleas. Light and electron microscopy showed a normal morphology in the controls. Aldosterone as a single treatment resulted in an increased activity of the marginal cells in the stria vascularis. Dissection induced a gradient of degenerative effects and cell loss in the intracellular and extracellular structures of the sensory cells, the stria vascularis and Reissner's membrane, which may be reversible. Subsequent administration of aldosterone induced severe damage and increased cell loss, which may be irreversible. Our findings demonstrate changes that may be reversible due to the compromising effect of a single treatment, and irreversible changes due to interaction of both compromising factors. These findings support our two-phase concept.

Animals↗

PubMed2002

The influence of radiotherapy on the lifetime of silicone rubber voice prostheses in laryngectomized patients.

OBJECTIVES: To establish a relationship between voice prosthetic lifetime in laryngectomized patients and the irradiation dose applied to the neck node levels (field of the neck) in which the major salivary glands are partially included. Furthermore, a possible relationship between voice prosthetic lifetime and the irradiation dose applied to the primary tumor site was studied. STUDY DESIGN: A retrospective analysis was performed on 101 patients after laryngectomy. METHODS: The records of 101 patients who underwent total laryngectomy between January 1993 and November 1999 at the Department of Otorhinolaryngology, University Hospital Groningen, The Netherlands, were analyzed. The following parameters were obtained: age, sex, radiotherapy, radiation fields, irradiation dose per field, tumor site, TNM classification, and valve insertion. RESULTS: Irradiation to extensive neck fields, including the submandibular glands, did not influence the voice prosthetic lifetime after laryngectomy. However, primary tumor doses exceeding 60 Gray significantly shortened the mean voice prosthetic lifetime per patient. CONCLUSIONS: This study identified an association between radiation on the primary tumor site with a dose equal to or more than 60 Gray and limited lifetimes of voice prostheses.

Adult↗