PubMed Health⌕ Search

Biomedical subjects

M H De Jong

Publications and source records attributed to M H De Jong.

7 recordsLinked to original sources
PubMed1999

Relation between IgG antibodies to foods and IgE antibodies to milk, egg, cat, dog and/or mite in a cross-sectional study.

BACKGROUND: Because IgG antibodies to foods can be detected before IgE antibodies to inhalants, increased levels of IgG antibodies to foods might be used as a predictor of IgE-mediated allergy in initially nonatopic children. OBJECTIVE: To examine the cross-sectional relation between IgG to foods (i.e. mixture of wheat and rice, mixture of soybean and peanut, egg white, cow's milk, meat, orange and potato) and specific IgE to cat, dog, mite, milk and egg white in 1-year-old children. METHODS: All atopic children (n = 120; 58 with and 62 without eczema) and a random sample of the nonatopic children (n = 144) of the Bokaal study were tested on their IgG response to foods. The IgG results of the food assays were dichotomized high or low using the 66th centile as a cut-off value. RESULTS: Atopic children more often had high IgG levels to foods than nonatopic children. IgG to egg white (OR = 7.50) and mixture of wheat and rice (OR = 4.79) were most strongly associated with positive specific IgE. In a stepwise logistic regression analysis egg white, mixture of wheat and rice, and orange were selected (OR = 3.76, OR = 2.43, and OR = 2.11, respectively). In children without eczema higher levels of IgG to foods were still significantly associated with atopy, which was most prominent for egg white, orange and cow's milk. CONCLUSION: An increased IgG antibody level to foods, especially to egg white, orange, and mixture of wheat and rice, indicates an increased risk of having IgE to cat, dog, mite, egg and/or milk allergens, even in the noneczematous group. Therefore, in another prospective study we are currently investigating the usefulness of IgG in early identification, i.e. before IgE antibodies can be detected, of children with an increased risk of developing allergic diseases in the future.

Allergens↗
PubMed1987

The growth of oral bacteria on saliva.

The present experiments were aimed at studying the degradation of salivary glycoproteins by the oral microflora. To this end, S. sanguis I strain Ny476 and S. sanguis II (S. mitior) strain Ny581 were grown continuously in human-whole saliva. Under these conditions, the strains produced a variety of cell-associated hydrolytic activities, including glycosidases, exo- and endopeptidases, and esterases. S. sanguis II generally exhibited higher levels of enzyme activity than did S. sanguis I, in particular of neuraminidase that was produced only by S. sanguis II. In accordance, S. sanguis II had a higher cell yield and consumed a higher proportion of the sugars and sialic acid in the glycoproteins than did S. sanguis I. Interestingly, S. sanguis I, which is devoid of neuraminidase, is known to have a lectin with specificity for sialic acid, whereas S. sanguis II has affinity for galactose residues in the glycoproteins. We propose that specific binding of glycoproteins by oral bacteria constitutes a mechanism to collect nutrients in the vicinity of the cell. The special ability of S. sanguis II to utilize saliva for growth was further exemplified by its selection in batch-wise enrichments of dental plaque on saliva. The microflora in these enrichment cultures always consisted of Peptostreptococcus micros, S. sanguis II, and Fusobacterium nucleatum as the dominant organisms. Further, S. mitis and Gemella haemolysans were generally found to be present. The enrichment cultures produced a wide variety of mainly cell-bound hydrolytic enzymes. This resulted in almost complete breakdown of salivary glycoproteins in the culture.

Bacteriological Techniques↗
PubMed1986

Effects of highly concentrated stannous fluoride and chlorhexidine regimes on human dental plaque flora.

The aim of this study was to determine the effect of an intensive antimicrobial treatment on the number of Streptococcus mutans, Streptococcus sanguis, Actinomyces viscosus/Actinomyces naeslundii, and the total Colony-forming Units (CFU) in plaque. The dentition of human volunteers was treated in a dental office with either chlorhexidine (5%) or stannous fluoride (8%). Following the office treatment with chlorhexidine, selected volunteers rinsed daily at home for seven or 49 days with chlorhexidine solution (0.2%), while another group flossed daily at home for seven days with dental floss impregnated with chlorhexidine. On days one, seven, 21, 35, and 49 after the local applications, we took saliva samples and plaque samples from fissures, smooth surfaces, and approximal areas. Chlorhexidine and stannous fluoride suppressed S. mutans and the Actinomyces species on all surfaces and in saliva. S. mutans on tooth surfaces was suppressed for approximately seven days and returned to the baseline level at day 21. A. viscosus/naeslundii was suppressed for more than seven days on the teeth. S. sanguis and the total CFU returned to the baseline level within seven days on all surfaces and in saliva. Rinsing or flossing with chlorhexidine suppressed S. mutans during the period of time that these supplements were used. Brushing for seven days with chlorhexidine gel (1%) without a preceding intensive chlorhexidine treatment had virtually no effect on S. mutans in approximal areas and in saliva, but suppressed S. mutans in fissures and on smooth surfaces.

Actinomyces↗
PubMed1986

Growth of micro-organisms from supragingival dental plaque on saliva agar.

The role of saliva in supporting the growth of dental plaque has scarcely been investigated. We have studied the growth and recovery of micro-organisms from dental plaque samples on saliva-agar plates, prepared from filter-sterilized wax-stimulated whole saliva. Under optimal conditions, the mean recovery of plaque samples on saliva agar was about 50% (range, 22-77) of the recovery on blood agar. Addition of 2.5 mmol/L dithiothreitol (DTT) strongly facilitated filter-sterilization of saliva, but DTT concentrations higher than 1 mmol/L reduced the recovery of plaque micro-organisms on saliva agar. Catalase (100 U/ml) offered protection against the inhibitory effect of DTT. Addition of glucose (1-5 mmol/L) increased only slightly the recovery of plaque micro-organisms on saliva agar. When supragingival plaque was plated on saliva- and blood-agar plates, the composition of the microflora isolated from saliva agar strongly resembled that isolated from blood agar. The predominant species--i.e., Streptococcus and Actinomyces--all grew on saliva agar though usually in numbers somewhat lower than those on blood agar. In addition, most species normally found only in low proportions in supragingival dental plaque were also found to grow on saliva agar. Collectively, the results lead to the conclusion that the supragingival microflora can utilize saliva as a complete source of nutrients.

Actinomyces↗
PubMed1981

Coenzyme M derivatives and their effects on methane formation from carbon dioxide and methanol by cell extracts of Methanosarcina barkeri.

Extracts of Methanosarcina barkeri reduced methanol and CO2 to CH4 in the presence of H2 and converted methanol stoichiometrically into CH4 and CO2 in the absence of H2. In dialyzed cell-free extracts these reactions were stimulated by 2-mercaptoethanesulfonic acid (coenzyme M) and some derivatives (acetyl and formylcoenzyme M and the oxidized form of coenzyme M), which could be converted to coenzyme M by enzyme systems present in the extracts. Methylcoenzyme M could not be used in these systems.

Carbon Dioxide↗
PubMed1976

Proton-motive force and the motile behavior of Bacillus subtilis.

Changes in the proton-motive force cause a transient change in the motile behavior of Bacillus subtilis cells. Both an increase and a decrease in the proton-motive force caused transient tumbling. Simultaneous decrease of proton-motive force and increase of attractant concentration lessens the response toward the attractant. A simultaneous increase of proton-motive force and increase of attractant concentration prolonges the response toward attractant. A hypothesis explaining the various effects is given.

Bacillus subtilis↗