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Biomedical subjects

P D'Haese

Publications and source records attributed to P D'Haese.

18 recordsLinked to original sources
PubMed2006

Partial prevention of long-term femoral bone loss in aged ovariectomized rats supplemented with choline-stabilized orthosilicic acid.

Silicon (Si) deficiency in animals results in bone defects. Choline-stabilized orthosilicic acid (ch-OSA) was found to have a high bioavailability compared to other Si supplements. The effect of ch-OSA supplementation was investigated on bone loss in aged ovariectomized (OVX) rats. Female Wistar rats (n = 58, age 9 months) were randomized in three groups. One group was sham-operated (sham, n = 21), and bilateral OVX was performed in the other two groups. OVX rats were supplemented orally with ch-OSA over 30 weeks (OVX1, n = 20; 1 mg Si/kg body weight daily) or used as controls (OVX0, n = 17). The serum Si concentration and the 24-hour urinary Si excretion of supplemented OVX rats was significantly higher compared to sham and OVX controls. Supplementation with ch-OSA significantly but partially reversed the decrease in Ca excretion, which was observed after OVX. The increase in bone turnover in OVX rats tended to be reduced by ch-OSA supplementation. ch-OSA supplementation increased significantly the femoral bone mineral content (BMC) in the distal region and total femoral BMC in OVX rats, whereas lumbar BMC was marginally increased. Femoral BMD was significantly increased at two sites in the distal region in OVX rats supplemented with ch-OSA compared to OVX controls. Total lumbar bone mineral density was marginally increased by ch-OSA supplementation. In conclusion, ch-OSA supplementation partially prevents femoral bone loss in the aged OVX rat model.

Absorptiometry, Photon↗
PubMed2005

[Development of a parent questionnaire for assessment of auditory behaviour of infants up to two years of age].

BACKGROUND: There is an increasing need for an instrument, which allows to quickly and reliably assess the auditory behaviour of infants and toddlers. SCIENTIFIC QUESTION AND OBJECTIVE: The objective of this study was to develop and validate the "LittlEARS Hearing Questionnaire", a tool for assessing auditory behaviour in children up to 24 months of age. METHODS: Questionnaire construction followed the principles of classical test theory. The psychometric properties of 45 questions on infant auditory behaviour were examined in a sample of 218 parents of normal hearing infants up to age 24 months. Parental responses also served for computing normative values of the development of early auditory behaviour by regression analysis. RESULTS: The final questionnaire contains 35 items, to be answered with either "yes" or "no". The sum of "yes"-answers yields an overall score, which can be compared to age-related normative values in order to appraise the age-appropriateness of the infant's auditory behaviour. The following scale characteristics have been found with the above sample: internal consistency: Cronbach's Alpha = 0.96; reliability: split-half r = 0.88; predictive accuracy: Guttman's Lambda = 0.96; correlation between overall score and age of the children: r = 0.91. CONCLUSION: The "LittlEARS Hearing Questionnaire" is suitable for the quick assessment of a little child's hearing behaviour, e. g. at physical examinations, at the postnatal hearing screening, or when evaluating rehabilitative measures.

Attention↗
PubMed2004

Head shadow, squelch, and summation effects in bilateral users of the MED-EL COMBI 40/40+ cochlear implant.

OBJECTIVE: The aim of the study was to investigate the impact of bilateral cochlear implant use on speech perception in noise in bilateral users of the MED-EL COMBI 40/40+ cochlear implants. DESIGN: Speech reception thresholds were measured in 21 subjects using the Oldenburg sentence test. Speech was always presented from the front. Noise was either presented from the front, from the left side, or from the right side. Each condition was measured for unilateral and bilateral implant use. RESULTS: For three subjects, the test was too difficult to be administered. The 18 subjects from whom a complete data set could be obtained showed a significant head shadow effect and summation effect for all test conditions, whereas the squelch effect was significant for noise from the left side only. Average effect sizes were significant for all effects and amounted to 6.8 dB for the head shadow effect, 0.9 dB for the squelch effect, and 2.1 dB for the summation effect. Effect sizes were not correlated with duration of deafness. CONCLUSIONS: Bilateral cochlear implant users can at least qualitatively benefit from the effects that are known from normal-hearing subjects, that is, head shadow, summation, and squelch effect. Bilateral cochlear implantation also reduces the performance gap between cochlear implant users and normal-hearing subjects.

Adolescent↗
PubMed2004

Sound localization in bilateral users of MED-EL COMBI 40/40+ cochlear implants.

OBJECTIVE: The purpose of the study was to investigate sound localization with bilateral and unilateral cochlear implants. DESIGN: Sound localization tests were performed on 20 bilaterally implanted MED-EL COMBI 40/40+ users. All subjects were bilaterally implanted during adolescence or later. Sound localization was tested in the frontal horizontal plane by using 9 equally spaced loudspeakers and speech-shaped noise bursts at randomized levels. RESULTS: The group of subjects who were bilaterally deafened after 5 to 6 yr of age (18 subjects) showed a statistically significant improvement in sound localization when using both implants, compared with when using only one. The mean deviation between the presentation azimuth and the response azimuth was 16.6 degrees when using both implants, which was on average 37.1 degrees smaller than when using one implant only. When adjusted for the localization error that was constant across loudspeakers, the mean deviation was 15.9 degrees for bilateral implant use, representing an improvement of 30.1 degrees over unilateral implant use. Statistical analysis showed that in this group, performance measures were not correlated with subject details such as age at onset of deafness or duration of unilateral implant use. In contrast, subjects who were bilaterally deafened before 6 yr of age (2 subjects) did not show a benefit in sound localization from bilateral implants. CONCLUSIONS: Bilateral cochlear implants offer a substantial benefit in sound localization to late-deafened, late-implanted subjects. The very limited data from early-deafened subjects implanted at a later age could suggest that these subjects may not benefit in sound localization from bilateral cochlear implants. It is possible that early implantation for early deafened subjects might allow better acquisition of spatial hearing, thus leading to improved localization performance.

Adolescent↗
PubMed2003

Speech recognition tests in sensorineural hearing loss.

The ability to understand speech must be considered the most important measurable aspect of human auditory function. Due to the innovative developments in hearing aids and cochlear implants, there has been a renewed interest in speech recognition testing. During recent years, the start of several multi-centre studies have increased the urge to come to some consensus on the use of different speech materials. In this article a global overview of existing types of speech material in Dutch will be given. For each type, there is a reference to similar speech audiometric tests in French, English and German.

Audiometry, Speech↗
PubMed2001

Rate influences on tone burst summating potential amplitude in electrocochleography: clinical(a) and experimental(b) data.

Electrocochleographic recordings of action and summating potentials are widely used in the electrophysiological assessment of endolymphatic hydrops (ELH). Increased amplitudes of the summating potential (SP) in response to tone burst stimuli are indicative of positive ELH. This study reports the effect of repetition rate of tone burst stimulation on the SP amplitude. Using transtympanic electrocochleography (ECochG), the SP in response to 1 kHz tone bursts was recorded in both a Ménière and a non-Ménière population. Absolute values of the SP were systematically higher in the Ménière group. Moreover, in the Ménière and non-Ménière groups, the response amplitudes of the SP at a repetition rate of 8.4 tone bursts/s were only 66 and 32%, respectively, of the maximal response amplitude which was obtained at the rate of 37.4 tone bursts/s. Additionally, in normal guinea pigs chronically implanted with a round window electrode, the SP was recorded to 0.5-16 kHz tone burst stimulations presented at 100 dB SPL with the same different repetition rates. Similar enhancement of the SP amplitude was observed from 8.4 to 37.4 stimuli/s, whatever the frequency. This effect is interpreted as an increased asymmetry of vibration of the cochlear partition, whose mechanical operating point would not return to the normal resting position at high repetition rates, since it is permanently shifted in ELH.

Acoustic Stimulation↗
PubMed2001

Hereditary otovestibular dysfunction and Ménière's disease in a large Belgian family is caused by a missense mutation in the COCH gene.

OBJECTIVE: To report the clinical, auditory, and vestibular characteristics of a nonsyndromic otovestibular dysfunction in a large Belgian family caused by a missense mutation of the DFNA9 gene: COCH. STUDY DESIGN: Retrospective study of the clinical, audiologic, and vestibular data of 60 genetically affected cases. SETTING: Tertiary referral center. PATIENTS: All members of a Belgian kindred who carry the genetic (P51S) defect linked to the inherited hearing and vestibular impairment. INTERVENTIONS: Diagnostic otologic, audiometric, and vestibular analysis and imaging. MAIN OUTCOME MEASURES: Pure tone audiometry, supraliminary audiometry. and vestibular investigation. RESULTS: The autosomal dominant inherited impairment was characterized by peripheral degeneration of the inner ear, leading to total deafness and bilateral vestibular areflexia. CONCLUSIONS: The genetically affected persons of a Belgian family shared a progressive sensorineural hearing loss starting between the third and sixth decade. Vestibular symptoms started at about the same age as the hearing loss. The vestibular symptoms consisted of instability in darkness, a tendency to fall sideways, light-headiness, a drunken feeling, and attacks of vertigo. Most of the patients reported tinnitus, and half of them reported pressure in the ears. Clinically, 9 of the 60 patients met the criteria for definite Ménière's disease, and another 13 and 17 patients met the criteria for probable or possible Ménière's disease, respectively. All 9 were older than the age of 35, but only 1 was older than 55 years, so more than 30% of the patients were between 35 and 55 years old. A specific pattern could be recognized in the evolution of the otovestibular impairment. Under the age of 35 years, almost all the affected family members had normal hearing, whereas above the age of 55 years, the hearing loss was at least moderate, and vestibular hypofunction occurred. In between, there was a transition period of two to three decades, when deterioration of the cochleovestibular function occurred, with a temporary audiometric and vestibular asymmetry.

Adult↗
PubMed2000

Audiometric analysis of a Belgian family linked to the DFNA10 locus.

OBJECTIVE: To report the otologic and audiometric characteristics of a nonsyndromic postlingual sensorineural hearing impairment in a Belgian family linked to DFNA10. STUDY DESIGN: Retrospective study of the otologic and audiometric data of 17 genetically affected persons. SETTING: Tertiary referral center. PATIENTS: All members of a Belgian kindred who carried the haplotype linked to the inherited hearing impairment of DFNA10. INTERVENTIONS: Diagnostic otologic and audiometric analysis. MAIN OUTCOME MEASURES: Pure-tone audiometry. RESULTS: To find the frequencies that were most affected by the genetic defect, the excess hearing loss of the 17 patients was calculated per frequency in comparison with the respective p50 and p95 thresholds of the normal population. CONCLUSIONS: The genetically affected persons of a Belgian family shared a progressive symmetric sensorineural hearing loss that started in the first to fourth decade. Thirty-five percent of the affected family members had tinnitus, and only one patient had very mild vestibular complaints. At onset, hearing losses were mainly situated at the midfrequencies. With increasing age, all frequencies became affected. The hearing loss was initially mild, with a spontaneous evolution to a moderate or severe hearing impairment. The progression of the hearing loss for the pure-tone average (between 0.5 and 4 kHz) was 1.08 dB/year for this family, compared with 0.50 dB/year and 0.35 dB/year at the 95th and 50th percentiles of the normal population, respectively.

Adult↗
PubMed1999

High prevalence of symptoms of Menière's disease in three families with a mutation in the COCH gene.

We report the genetic analysis of one large Belgian and two small Dutch families with autosomal dominant non-syndromic progressive sensorineural hearing loss associated with vestibular dysfunction. Linkage studies in the Belgian family mapped the disease to the DFNA9 locus on chromosome 14. Mutation analysis of the COCH gene, which is responsible for DFNA9, revealed a missense mutation changing a highly conserved residue. One of the patients, who had an earlier age of onset in comparison with most of the affected family members, was shown to be homozygous for the mutation. After the mutation was found in the Belgian family, we discovered that the same missense mutation was also present in two Dutch families with similar cochleo-vestibular symptoms. In all three families with hearing loss and imbalance problems, >25% of the patients showed additional symptoms, including episodes of vertigo, tinnitus, aural fullness and hearing loss. Clinically, these symptoms are consistent with the criteria for Menière's disease. The importance of genetic factors in Menière's disease has been suggested on many occasions, but this study is the first report of a mutation in a gene leading to the symptoms of Menière's disease in a significant portion of the carriers. The COCH gene may be one of the genetic factors contributing to Menière's disease and the possibility of a COCH mutation should be considered in patients with Menière's disease symptoms.

Chromosomes, Human, Pair 14↗
PubMed1998

Lead absorption and renal dysfunction in a South African battery factory.

OBJECTIVES: To test the association between inorganic lead (Pb) exposure, blood pressure, and renal function in South African battery factory workers, with both conventional and newer measures of renal function and integrity. METHODS: Renal function measures included serum creatinine, urea, and urate (n = 382). Urinary markers (n = 199) included urinary N-acetyl-beta-D-glucosaminidase (NAG), retinol binding protein, intestinal alkaline phosphatase, tissue non-specific alkaline phosphatase, Tamm-Horsfall glycoprotein, epidermal growth factor, and microalbuminuria. RESULTS: Mean current blood Pb was 53.5 micrograms/dl (range 23 to 110), median zinc protoporphyrin 10.9 micrograms/g haemoglobin (range 1.9 to 104), and mean exposure duration 11.6 years (range 0.5 to 44.5). Mean historical blood Pb, available on 246 workers, was 57.3 micrograms/dl (range 14 to 96.3). After adjustment for age, weight and height, positive exposure response relations were found between current blood Pb, historical blood Pb, zinc protoporphyrin (ZPP), and serum creatinine and urate. Blood pressure was not associated with Pb exposure. Among the urinary markers, only NAG showed a positive association with current and historical blood Pb. CONCLUSION: An exposure-response relation between Pb and renal dysfunction across the range from < 40 to > 70 micrograms/dl blood Pb was found in this workforce, with conventional measures of short and long term Pb exposure and of renal function. This could not be explained by an effect on blood pressure, which was not associated with Pb exposure. The findings probably reflect a higher cumulative renal burden of Pb absorption in this workforce in comparison with those in recent negative studies. The results also confirm the need for strategies to reduce Pb exposure among industrial workers in South Africa.

Acetylglucosaminidase↗
PubMed1986

Lead nephropathy.

In the past, lead poisoning was recognized when classical symptoms of acute intoxication were present and the blood lead was elevated. The EDTA test is presently the most reliable method for detecting excessive lead stores. We used the EDTA lead-mobilization test to demonstrate excessive past lead absorption as a cause of renal disease in lead workers and in both gouty and hypertensive patients with renal failure. These studies show that lead nephropathy occurs in the absence of acute intoxication and that occult poisoning often goes unrecognized because of inappropriate diagnostic criteria.

Adult↗
PubMed1984

Determination by flameless atomic absorption of aluminium in serum and hair for toxicological monitoring of patients on chronic intermittent haemodialysis.

Determination of aluminium in serum of patients on chronic intermittent haemodialysis is of paramount importance in the prevention or early diagnosis of aluminium intoxication. We present a new method based on flameless atomic absorption spectroscopy, in which the serum matrix is destroyed by oxygen. A comparison has been made between the described method and another procedure which is used in the Laboratory of Toxicology in Ghent, with favourable results. In addition, a method is presented for the determination of aluminium in hair, in which special attention has been paid to the cleaning of the hair samples prior to destruction. As yet it cannot be concluded whether aluminium concentrations in hair give a better representation of the body burden than serum levels do.

Aluminum↗
PubMed1984

Serum ferritin as a guide for iron stores in chronic hemodialysis patients.

The serum ferritin (SF) level was measured in 58 chronic hemodialysis (CHD) patients (46 living and 12 deceased subjects) and compared to bone marrow iron concentrations, cytological bone marrow iron stores (BMIS), and histological BMIS. In the 12 deceased subjects, liver iron concentrations, histological liver parenchymal, and Kupffer cell iron stores were also studied. The mean SF level of the whole group was 302 +/- 251 ng/ml (mean +/- SD). No close relationship was found between transferrin saturation and cytological BMIS. A high correlation was found between SF level and cytological BMIS (Spearman rank rs = 0.74). In the deceased CHD patients a close correlation was observed between histological parenchymal liver iron stores and histological Kupffer cell iron stores, but not between liver and bone marrow iron stores. A good correlation was found between SF levels and liver iron concentrations. It is concluded that in CHD patients SF levels are higher than in healthy controls, even in the absence of iron therapy (except in the form of blood transfusions); in some of these patients iron is disproportionately stored in the bone marrow and the liver. Although the level of BMIS cannot be estimated unequivocally from an SF measurement in every CHD patient, SF levels provide useful estimates of BMIS.

Adult↗
PubMed1984

Ultrastructural localization of aluminum in patients with dialysis-associated osteomalacia.

Using laser microprobe mass analysis, we studied the ultrastructural localization of aluminum in liver and bone tissue of chronic-hemodialysis patients with proven aluminum-induced osteomalacia. In the liver, aluminum was observed to be almost exclusively associated with iron. Detectable aluminum and large amounts of iron were found in lysosomes of both hepatocytes and Kupffer cells. In bone, aluminum was localized at the osteoid/calcified-bone interface and also was associated with iron in some cases.

Adult↗
PubMedDate not supplied

Urinary biomarkers as indicators of renal disease.

Using modern technology, minute quantities of LMWP, prostanoids, growth factors, intra-renal and extra-renal enzymes can be measured in urine. Excretory patterns that are characteristic for site and mechanism of renal injury often can be found. It is possible to recognise urinary biomarker patterns that suggest the putative environmental nephrotoxin. Our own studies performed in subjects with low level occupational and environmental exposures in New Jersey confirm the pattern specificity and threshold effects for Cr, Hg and Pb. In addition, we have been able to show that increased NAG and IAP excretion following Pb exposure correlates with current (blood Pb) but not with the cumulative Pb burden (bone Pb). The relatively specific characteristic patterns of biomarker excretion are lost as renal failure progresses. Moreover, renal injury that results in tubular proteinuria may not progress to renal failure. Nevertheless, urine biomarkers can help to establish acceptable levels and identify the need for long term surveillance to ascertain when clinical renal disease may result.

Adult↗