The middle ear of cleft palate patients in their early teens: a literature study and preliminary file study.

OBJECTIVES: Middle ear disease is a frequent problem in young children with cleft palate (CP). Less is known about otological status in the adolescent CP population. The aim of this study is to provide an overview of current knowledge in the literature concerning the aetiology of middle ear disease in CP patients and the middle ear status of older children with CP, and to compare the situation in our centre to this background through an assessment of the otological status of patients in our CP population. MATERIAL AND METHODS: A literature review was conducted to summarise current knowledge about middle ear status in CP patients. A retrospective analysis was performed of the medical records of 20 CP patients between the ages of 10 and 15 who were treated and followed at the University Hospitals Leuven. The available otological data, otoscopic findings, information about hearing and surgery performed was collected for each patient when aged three and above ten years. RESULTS: Current knowledge indicates that middle ear function improves as CP patients get older. In our study, otoscopic appearance was acceptable in 63% of ears of children aged over ten years of age. Otitis media with effusion (OME) was far less frequent above this age than around the age of 3, with a decrease from 50% to 13% of all ears. Above the age of 10, tympanic perforations were present in 13% of ears and retraction of the tympanic membrane in 23%. CONCLUSIONS: Despite a very high incidence of OME in young CP patients, the long-term otological prognosis is not necessarily sinister. A favourable natural evolution, diligent otological follow-up, early diagnosis and treatment of middle ear disease with the use of tympanostomy tubes are the likely contributors to the acceptable otological result in older CP patients.

Effect of trace metal availability on coccolithophorid calcification.

The deposition of atmospheric dust into the ocean has varied considerably over geological time. Because some of the trace metals contained in dust are essential plant nutrients which can limit phytoplankton growth in parts of the ocean, it has been suggested that variations in dust supply to the surface ocean might influence primary production. Whereas the role of trace metal availability in photosynthetic carbon fixation has received considerable attention, its effect on biogenic calcification is virtually unknown. The production of both particulate organic carbon and calcium carbonate (CaCO3) drives the ocean's biological carbon pump. The ratio of particulate organic carbon to CaCO3 export, the so-called rain ratio, is one of the factors determining CO2 sequestration in the deep ocean. Here we investigate the influence of the essential trace metals iron and zinc on the prominent CaCO3-producing microalga Emiliania huxleyi. We show that whereas at low iron concentrations growth and calcification are equally reduced, low zinc concentrations result in a de-coupling of the two processes. Despite the reduced growth rate of zinc-limited cells, CaCO3 production rates per cell remain unaffected, thus leading to highly calcified cells. These results suggest that changes in dust deposition can affect biogenic calcification in oceanic regions characterized by trace metal limitation, with possible consequences for CO2 partitioning between the atmosphere and the ocean.

The determination and distribution of Zn in surface water samples collected in the northeast Atlantic Ocean.

Dissolved Zn concentrations were determined in surface water samples collected on-line along transects in the eastern North Atlantic in spring (March 1998). Two frontal zones could be identified in the research area by a change in salinity, temperature and nutrient concentrations. One zone was identified at 42 degrees N, separating the North Atlantic central water (NACW) and the Atlantic surface water (ASW) from each other, and another one crossing the continental slope at 12 degrees and 8 degrees E, respectively. Variability in Zn concentrations was observed near these zones, not only as a result of a change of water mass, but also due to external Zn sources. Surface Zn concentrations were 0.5-1 nM and 2 nM in the NACW and ASW, respectively, increasing to 4 nM over the continental shelf and finally 5-6 nM in the English Channel. Contributions of Zn derived from shelf sediments appear to be the major source for the enriched surface values in the continental zone.

Trace metals in a littoral foodweb: concentrations in organisms, sediment and water.

Cadmium, lead, zinc and copper concentrations were determined in 15 species of freshwater macro-invertebrates collected from a littoral foodweb. Indications of a biomagnification process, in which predators had a higher concentration than their prey, were only found in the case of zinc. Organisms with copper as an essential component of their haemolymph, such as Crustacaea, Gastropoda and Bivalvia, contained higher concentrations of that metal than other species. Another important factor in the determination of trace metal concentrations, apart from physiological equipment, was body weight, resulting in higher concentrations in smaller, and lower concentrations in larger, organisms. This seemed to be the case within populations of single species, as well as in different species of deposit feeders. Furthermore, feeding habit, proximity to the sediment and physico-chemical factors appeared to be determining factors for trace metal concentrations in macro-invertebrates. The results of this study are related to ecotoxicological theories which explain the causes of pollutant residues in organisms. It is concluded that various explanations for the differences in pollutant residues, e.g. trophic level, feeding habit, body weight, association with the substrate, physiological equipment and abiotic factors, are valid.

The fate of trace metals during the metamorphosis of chironomids (diptera, chironomidae).

The fate of the trace metals zinc, cadmium and copper during the metamorphosis of chironomids was studied under field and experimental conditions. Field observations demonstrated a significant decrease in the trace metal body burden of larvae and imagines of Stictochironomus histrio Fabricius. No such difference were noted between successive developmental stages of Chironomus anthracinus Zett. The exuviae of both species contained small amounts of trace metals. Experiments, in which larvae of S. histrio and C. riparius Meigen were individually exposed, showed that larvae of both species accumulated substantial amounts of zinc and cadmium. For these metals, a transfer to pupae and imagines occurred. However, pupae had a lower body burden than larvae, and imagines a lower body burden than the pupae. Copper was also accumulated in the larvae, but it was excreted almost completely before the pupal stage. Elimination pathways of the trace metals during metamorphosis and the ecotoxicological consequences of trace metal transfer are discussed.