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Biomedical subjects

J Arends

Publications and source records attributed to J Arends.

At least 217 records · Page 12Linked to original sources
PubMed1984

Measurement of the surface free energy of bacterial cell surfaces and its relevance for adhesion.

An experimental technique is described to determine contact angles on bacterial layers deposited on cellulose triacetate filters. Measurements with water, water-n-propanol mixtures, and alpha-bromonaphthalene were employed to calculate surface free energies of various oral bacteria. Differences of 30 to 40 erg cm-2 were obtained for four different bacterial species isolated from the human oral cavity, if the concept of dispersion and polar surface free energies is applied. The free energies obtained were used to calculate interfacial free energies of adhesion of these bacteria from saliva onto tooth surfaces. Bacterial adhesion is energetically unfavorable, if the enamel surface free energy is less than 50 erg cm-2.

Adhesiveness↗
PubMed1984

Crystallographic structure of enamel surfaces treated with topical fluoride agents: TEM and XRD considerations.

The crystallographic structure of surface coatings produced by three topical fluoride agents deposited by a single application on intact human enamel surfaces was investigated by light- and dark-field transmission electron microscopy, as well as by electron and x-ray diffraction. The agents studied were an acidic silane fluoride lacquer, a neutral NaF lacquer, and an APF gel. The smallest coherently diffracting particles were CaF2 microcrystallites 4-15 nm in diameter. Large apatite-like crystals, approximately 1 micron in length, were also observed in the outer surface coating produced by the silane fluoride lacquer.

Animals↗
PubMed1984

The effect of topical fluoride applications on the surface free energy of human enamel--an in vitro study.

The surface free energy gamma s and its polar and dispersion components gamma Sp and gamma Sd were determined from contact angle measurements on human enamel treated with sodium fluoride, acidulated phosphate fluoride (APF), and aminfluoride solutions. Sodium fluoride solutions only slightly influenced the surface free energy component gamma Sp. The gamma Sp value of the APF-treated human enamel increased from 52 to 66 erg X cm-2. The gamma Sp value after aminfluoride treatment decreased from 52 to 19 erg X cm-2. The gamma Sd values remained about 35 erg X cm-2 for all specimens measured. It is suggested that aminfluoride-treated enamel surfaces may exhibit a reduced tendency for bacterial adhesion.

Acidulated Phosphate Fluoride↗
PubMed1984

Normal and abnormal prolactin levels during human pregnancy. Lack of influence on fetoplacental endocrine function.

Serial measurements of serum prolactin (PRL), chorionic gonadotropin (hCG), estradiol and progesterone were performed during 16 normal pregnancies. The same hormone analyses were performed in a woman with the galactorrhea-amenorrhea syndrome and a pituitary adenoma during two pregnancies, with and without continued treatment with bromocriptine throughout gestation. The study indicates that marked differences in circulating PRL levels do not influence the fetoplacental hormone levels. Furthermore, tumor expansion may possibly be prevented and successful breast-feeding can be achieved after treatment with bromocriptine throughout gestation.

Adenoma↗
PubMed1984

Testicular carcinoma in Denmark 1976-1980. Stage and selected clinical parameters at presentation.

Since Jan. 1, 1976 practically all new cases of germ cell tumours of the testis in Denmark have been included in the Danish Testicular Carcinoma Study (DATECA), permitting detailed registration of data concerning histology and stage at the time of diagnosis. The incidence of carcinoma of the testis in Denmark continues to be high with a crude rate of 8 to 9/100 000 males per year. During the past 5 years the size of the primary tumours has decreased. Parallel to this, the rate of metastatic spread has decreased for seminoma, while no such change has been observed for non-seminomatous tumours. Data are presented on histology and stage for 1058 consecutive patients.

Adolescent↗
PubMed1984

Tumour markers in testicular germ cell tumours. Five-year experience from the DATECA Study 1976-1980.

Since Jan. 1, 1976, nearly all new cases of testicular germ cell tumours have been included in the Danish Testicular Carcinoma Study (DATECA), and have been monitored by the tumour markers alpha-fetoprotein (AFP) and human chorionic gonadotropin (HCG). During the first five years, 1058 patients participated in the investigation, but only 603 of these patients were followed by preoperative as well as postoperative marker determinations in serum. The overall prevalence of marker positivity, i.e. elevated preoperative values for AFP and/or HCG, was 8 per cent for seminoma patients and 60 per cent for non-seminoma patients. Elevated levels of serum AFP and HCG were correlated to the presence of endodermal sinus tumour and choriocarcinoma elements, respectively, in the primary tumour. The presence of increased marker concentration in serum was correlated stage (higher percentage in higher stages) and to prognosis (marker negative patients had a better prognosis than marker positive patients). Marker production by seminoma patients seems to indicate a poor prognosis, especially for HCG producing seminomas.

Chorionic Gonadotropin↗
PubMed1984

The surface free energy of human dental enamel.

The surface free energy is a definite factor in the adhesion of micro-organisms to host surfaces, such as tooth surfaces. The surface free energy gamma s can experimentally be determined by means of a series of contact angle measurements with various liquids. Employing the concept of polar and dispersion components, it was found, that gamma s of ground and polished human enamel is 88 +/- 9 erg.cm-2. This value is of the same order of magnitude as obtained for hydroxyapatite (the main mineral component of enamel) and fluorapatite. Fluoride applications on human enamel, frequently employed in dentistry, greatly influence the surface free energy. Application of various fluorides gave different results: Aminfluorides reduced gamma s to 62 +/- 5 erg.cm-2; APF raised gamma s to 107 +/- 11 erg.cm-2; NaF hardly influenced gamma s X gamma s remained 87 +/- 9 erg.cm-2. Adsorption of salivary proteins (pellicle formation) influences these differences. In vivo pellicle formation on FEP (gamma s = 17 erg.cm-2) increased gamma s to 41 erg.cm-2, Diacryl (gamma s = 76 erg.cm-2) increased gamma s to 117 erg.cm-2, while on sintered hydroxyapatite (gamma s = 80 erg.cm-2) gamma s increased to 118 erg.cm-2.

Dental Enamel↗
PubMed1984

In vivo remineralization of artificial subsurface lesions in human enamel. I.

In this paper in vivo remineralization of artificial subsurface lesions in human enamel, placed in partial prostheses of 30 patients during 3 months is presented. The patients were divided into 3 groups. Group A brushed daily with H2O: group B brushed with H2O and rinsed with a neutral 50 ppm F- solution and group C brushed with a neutral 1500 ppm F- toothpaste. Microhardness indentation measurements were carried out at the start of the experiment and after 2, 4, 16, 20, 44, 58 and 87 days. After 3 months, the indentation length reductions (in %) were for group A, B and C 16, 13 and 20%, respectively. These differences were all statistically significant at least at the p less than 0.05 level. In conclusion, subsurface lesions remineralize very slowly in vivo, much slower than in vitro situations. The remineralization rate is relatively fast in the first 2 weeks; for longer periods the remineralization rate of subsurface enamel lesions is very slow.

Dental Caries↗
PubMed1984

Microradiography of in vivo remineralized lesions in human enamel. II.

The purpose of this work was to investigate mineral deposition and redistribution in subsurface human artificial enamel lesions during in vivo remineralization period of 3 months. The enamel lesions were placed in lower prostheses of 30 patients, divided in 3 groups. Group A brushed daily with H2O; group B brushed with H2O and rinsed with a neutral 50 ppm F solution and group C brushed with a neutral 1500 ppm F toothpaste. The technique employed was microradiography. Initially the average vol % of mineral in the lesion body was 47%. After 3 months remineralization in vivo the vol % of mineral in the lesion body was for group A, B and C: 50.7, 48.7 and 53.1 vol %, respectively. The average lesion depth decreased for groups A, B and C 18, 13 and 25 microns respectively over 3 months. The original lesion depth was +/- 100 microns. The microradiographic data show conclusively that mineral is deposited "de novo" inside subsurface lesions. The remineralization percentages are for the control, rinse and brush group 20%, 15% and 31%, respectively.

Dental Caries↗
PubMed1983

Dispersion and polar surface free energies of human enamel.

In this study, the dispersion (gamma ds) and polar (gamma ps) surface free energies of human enamel with and without an acquired enamel pellicle and of crystalline hydroxyapatite were determined from contact angle measurements. The results show that gamma ps is strongly influenced by the presence of a pellicle; the total surface free energy (gamma s) is considerably smaller for enamel with an acquired pellicle than for enamel without an acquired pellicle. Enamel without an acquired enamel pellicle shows surface free energies comparable with those of crystalline hydroxyapatite.

Dental Enamel↗