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Biomedical subjects

A Groeneveld

Publications and source records attributed to A Groeneveld.

At least 37 records · Page 2Linked to original sources
PubMed1989

[Implications from an increase in wealth for the dental health care].

After a theoretical introduction concerning the relation between wealth and dental health, the consequences as deducted from a scenario which implies a yearly increase of income for the whole population of 1.5% are presented. The main results are a strong income-dependency for the implications of an increase in income for the utilization of dental care. People from the lower socio-economical classes are expected to show increase in the amount of care consumed, while people from the higher socio-economical classes are expected to show a need for more expensive and more preventive treatment. The improvement of the oral health situation due to an increase of wealth is not expected to be significant.

Dental Care↗
PubMed1988

A new radiometric assay for the quantitation of surface-bound IgG on sensitized erythrocytes.

We have developed a sensitive, straightforward method for the quantitation of surface-bound IgG on sensitized erythrocytes. The assay is based on the consumption by sensitized cells of anti-IgG antiserum. The remaining anti-IgG is quantitated in a second incubation by precipitation with 125I-IgG in the presence of polyethylene glycol. Calibration curves for this assay were constructed using known amounts of unlabeled IgG. The method can be performed in microtitre plates and eliminates the use of purified anti-erythrocyte antibodies, or highly purified specific anti-IgG antisera. The results were completely consistent with those of immunofluorescence assays, but our method was much more sensitive, less than 500 molecules of IgG per cell being detected reproducibly. The technique is not laborious and takes much less time than previously described methods with similar sensitivity. As an example of the applicability of this test, the implications of ligand density for the detection by EA rosetting of Fc receptors on human monocytes are shown. The results suggest that a large variation exists in the affinity of the different types of Fc receptors for their ligands.

Animals↗
PubMed1985

Effect of time, degree of saturation, pH and acid concentration of buffer solutions on the rate of in-vitro demineralization of human enamel.

The rate of demineralization of the artificial caries-like process was measured using two methods. The rate calculated from microradiography of the demineralized enamel appeared to be equal to the one calculated from calcium and phosphate analysis of the demineralizing buffer. In small volumes of demineralizing solution, the rate of demineralization decreased with time, due to the increase in saturation of the solution during the demineralization of the enamel. With increasing saturation, with respect to hydroxyapatite, and with increasing pH the rate of demineralization decreased. Increasing acid concentration had a marked influence only at the lower concentrations; a further increase had no effect on the rate of demineralization.

Buffers↗
PubMed1985

Longitudinal study of prevalence of enamel lesions in a fluoridated and non-fluoridated area.

The aim of this study was to examine longitudinally the effect of water fluoridation on the prevalence of enamel lesions in children 7-18 yr of age. 93 children in Tiel (1 ppm F-) and 103 children in Culemborg (0.1 ppm F-) were examined every other year at 7, 9, 11, 13 and 15 yr of age. A supplementary examination was carried out when these children reached the age of 18. Children in Tiel had access to water fluoridation from birth. The total number of lesions, including enamel lesions, on the buccal as well as on the occlusal surfaces was approximately the same in both areas in children 15 and 18 yr of age. Approximal lesions were scored on standardized bitewing radiographs. A large proportion of enamel lesions could not be detected on radiographs. In a fluoridated area a high percentage of all lesions remain in the stage of enamel caries lesions. On buccal surfaces 93% and on approximal surfaces 86% of all lesions had not progressed into the dentin. In Culemborg these percentages were 65 for approximal as well as for buccal surfaces. At the initiation of lesions, at younger ages, only a small retardation of the process was observed, but caries progression beyond the stage of enamel caries was markedly reduced in the fluoridated area. No pre-eruptive effect could be observed if the total number of lesions, including enamel lesions, from Tiel and Culemborg were compared.

Adolescent↗
PubMed1984

Changing protein patterns during lens cell aging in vitro.

Changes in biosynthesis of lens proteins upon culturing have been studied by one- and two-dimensional gel electrophoretic techniques. In primary cells still growing on the capsule, alpha B2-crystallin is synthesized in a relatively high amount next to the main cytoskeletal constituents actin, tubulin and vimentin. In addition, a minor amount of beta Bp seems to be synthesized too. When the cells grow off the capsule, alpha-crystallin synthesis diminishes. beta-Crystallin synthesis continues at a low rate in cells growing on plastic or in cells forming 'lentoid bodies'. When the cells are subcultured, the synthesis of actin and vimentin becomes more pronounced, while tubulin synthesis is no longer detectable after three transfers. The relative amount of vimentin decreases, as compared to actin, during aging and elongation of the cells. When the cells have been transferred ten times and have started to elongate, a 55 kDa protein doublet differing from tubulin is observed in the two-dimensional gel patterns. We observed that elongation of lens cells in culture is accompanied by an increase in the synthesis of a polypeptide of the 26 kDa region. Furthermore, a major glycoprotein is found in the 130 kDa region, but overall glycosylation of proteins seems to decrease during lens cell elongation in vitro.

Actins↗
PubMed1984

The effect of undissociated acetic-acid concentration of buffer solutions on artificial caries-like lesion formation in human tooth enamel.

A chemical system for lesion production was used. The influence on lesion characteristics of the concentration of undissociated acetic acid in a calcium and phosphate-containing buffer solution was investigated. Artificial lesions obtained after demineralization in buffers with a pH of 4.0, 4.5, 5.0 or 6.0 at 5 or 6 different acid concentrations for different demineralization times were investigated micro-radiographically. The lesion characteristics studied were: the mineral content of the surface layer; the mineral content of the body of the lesion; and the depth at which these mineral levels were reached; the depth of the lesion. The concentration of undissociated acetic acid had little effect on the lesion characteristics at low pH. When lower concentration buffers at pH 6.0 were used, the effect was more pronounced. At this level, the buffer capacity of the acetic acid/acetate buffer is small.

Acetates↗
PubMed1984

Effect of annual application of polyurethane lacquer containing silane-fluoride.

The effect of an annual application of a F- -lacquer on dental caries was investigated in a 3-yr study. Two groups of children 10 and 12 yr of age at baseline were examined. At the end of the study no significant difference in DMFS could be detected between test and control group. The following factors might have affected this negative result: firstly, the use of other forms of F- supplementation, secondly, the relatively low caries experience in both groups and thirdly, the frequency and mode of application of the F- -lacquer.

Acrylic Resins↗
PubMed1983

The mineral content of human enamel studied by polarizing microscopy, microradiography and scanning electron microscopy.

The total observed birefringence and mineral content of the outer 300 micron of longitudinal sections of sound buccal premolar enamel were measured and three-dimensional contour maps were made. Using similar contour maps of calcium, carbonate and magnesium content from the literature, it seemed possible to explain the differences between the contour maps of total observed birefringence and mineral content. Scanning electron micrographs provided information about the orientation of the prisms. The cervical part of the enamel had a high intrinsic birefringence which may explain the difference between mineral content and total observed birefringence. This high intrinsic birefringence may be caused by a high carbonate content in cervical enamel.

Bicuspid↗