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Biomedical subjects

C W Van Wyk

Publications and source records attributed to C W Van Wyk.

At least 19 recordsLinked to original sources
PubMed2001

Diffusion of reduced arecoline and arecaidine through human vaginal and buccal mucosa.

Because alkaloids from areca nut, arecoline and arecaidine, have been implicated in the development of oral submucous fibrosis, we determined their diffusion kinetics through human buccal and vaginal mucosa. Four clinically healthy vaginal mucosa specimens (mean patient age +/- standard deviation: 47 +/- 15 years; age range: 31-60 years) and 4 buccal mucosa specimens from 2 male patients and 2 female patients (mean patient age +/- standard deviation: 31 +/- 9 years; age range: 17-53 years) were obtained during surgery. In vitro flux rates of reduced arecoline and arecaidine (r-arecoline and r-arecaidine) were determined by use of a flow-through diffusion apparatus. Analysis of variance, a Duncan multiple range test, and an unpaired t-test were used to determine steady state kinetics and flux differences over time intervals. Although statistically significant differences were observed between flux values for both alkaloids and tissues at certain time points, these were not considered to be of biological (clinical) significance. However, the flux rates across both mucosa of r-arecoline were significantly higher statistically than those of rarecaidine. The findings demonstrated the differences in the diffusion kinetics between r-arecoline and r-arecaidine across human buccal and vaginal mucosa, an observation that could be explained in terms of their ionisation characteristics. Additionally, the results obtained further support the hypothesis that human vaginal mucosa can be used as a model for buccal mucosa in studies of permeability to various chemical compounds.

Adolescent↗
PubMed1991

Toothbrushing with the root of Euclea natalensis.

The custom of cleaning teeth and the gums with a chewed root of the tree Euclea natalensis, in the belief that it benefits oral health, is practised in South Africa by married women of an African Zanzibari community. The root of E. natalensis contains naphthoquinones which are bactericidal and, as they are also pigments, the mouths of the root users are stained bright orange. Samples of fresh root were tested against Streptococcus mutans and organisms in saliva and from deep periodontal pockets. Aerobic as well as anaerobic bacterial growth was suppressed in all instances. In addition we compared the plaque index (Silness et Löe), the periodontal index (CPITN), the DMFT and the state of the oral mucosa of root users and non-users. No significant differences were recorded in any of the variables. Although the beneficial effects claimed for this custom may have scientific validity, it is concluded that the daily practice is too limited to have a demonstrable beneficial effect.

Adult↗
PubMed1989

Evaluation of inbred germ-free Fischer 344 albino rats as an experimental model for oral candidiasis.

Inbred germ-free Fischer 344 albino rats were evaluated as models for experimental candidiasis in order to investigate bacterial interaction with Candida albicans. Female rats were exposed to C. albicans in their drinking water and killed at intervals from 2 to 22 days after initial contact with the contaminant. C. albicans was cultured from their mouths from day 2 but from day 12 the number of colonies decreased. From day 2 to 9 all rats showed oral histological signs of candidal infestation, but after 9 days the number declined to 3 out of 9 at 22 days. The dorsal surface of the tongue was the best histological indicator of candidal infestation. All the rats had tongue lesions from day 4 to 9, and from day 6 there was also a concomitant localized loss of filiform papillae. The number of rats with all forms of tongue involvement also decreased after 9 days with only 3 out of 9 affected at 22 days. It is concluded that Fischer 344 inbred germ-free rats can be used on a limited scale as a model for candidiasis and bacterial interaction with C. albicans, the dorsal surface of the tongue would be the best site for studying candidal experimental lesions and it is probable that better results can be achieved with complete standardization of contamination and preparation procedures.

Animals↗
PubMed1988

The oral features of betel nut chewers without submucous fibrosis.

This study examines the betel nut chewing practices, and the resulting oral clinical and histological features of 20 chewers who were without the diagnostic characteristics of submucous fibrosis. All chewed pan; the average duration of the habit was 10.5 years and the average frequency 7.1 quids per day. Eleven complained of intermittent burning and soreness of the mouth and 12 depicted blanching of the mucosa. Only 2 subjects were free from symptoms or signs. Eighteen chewers revealed an abnormal epithelium with extensive hyperplasia in 10 subjects and the rest demonstrated varying degrees of hyperplasia with abnormal maturation of the epithelium. Seven of the latter showed atypia as well. Parakeratosis was present in 7 and pigment incontinence in 9. Varying degrees of chronic inflammation featured in 17 specimens and the lamina propria was dense and hyalinized in 9. No correlation was found between the histological features, the clinical features and the various aspects of the habit. It is concluded that chewing betel nut will lead to pathological changes in the mucosa, but that neither the frequency nor the duration of the habit are accurate predictors of the extent of these changes or when they are likely to occur.

Adolescent↗
PubMed1987

Primary intraosseous carcinoma involving the anterior mandible.

A case is reported of a primary intraosseous carcinoma arising in the anterior mandible with metastasis to the submandibular lymph node in a 69 year-old Caucasian female. The patient initially presented with a burning sensation in the oral cavity in 1983, when no obvious pathological finding was noted; she returned 2 years later with a firm buccal swelling which had increased in size after the extraction of a mobile tooth. The tumour proved to be a primary intraosseous intraosseous carcinoma; extensive investigation did not reveal a primary carcinoma elsewhere.

Aged↗
PubMed1987

Human papillomavirus (HPV) in oral squamous cell papillomas.

One hundred and forty oral squamous cell papillomas (SCPs) were subjected to immunocytochemical staining for papillomavirus antigen using the immunoperoxidase-PAP method 41% of the oral squamous papillomas showed positive intranuclear staining, 50% were negative and the remaining 9% showed both intranuclear and cytoplasmic staining. In view of these findings it is suggested that a review of the etiology of lesions diagnosed as oral SCPs should be considered.

Female↗
PubMed1987

Elastic fibre and hyaluronic acid in the core of human palatal rugae.

The core within the palatal rugae of humans contains elements which are believed to contribute to the maintenance of its shape. A cross-sectional study was represented by 23 specimens of human palatal mucosa aged 3 months to 80 years and stained for sulphated and non-sulphated glycosaminoglycans (GAG), elastic tissue and collagen. Statistical correlations between core margin definition and age and elastic content were significant (p less than 0.005 and p less than 0.025). It was concluded that the main structural element of a ruga is not elastic tissue or collagen but GAG which by its hydrophilic nature causes the tissue to swell and contributes to the maintenance of the shape of a ruga throughout life.

Adolescent↗
PubMed1984

Abnormal keratohyalin-like forms in leukoedema.

Electron microscopic, histochemical and light-microscopic studies were carried out on biopsy specimens of 12 cases of leukoedema and on the desquamated epithelial cells of a further 50 examples. For comparison, similar observations were made of 4 examples of healthy cheek mucosa and 29 cases of a variety of pathological conditions of the oral mucosa. Only in leukoedema were a series of structures encountered which consisted of an aggregation of ribosomes and electron dense masses, or a network of electron-dense material, or an electron-dense network with a central dense core or a solid body with a few central cavities. Histochemical stains and RNA extraction studies showed that they are probably abnormal forms of keratohyalin granules and that ribosomes is an important component of their composition.

Cytoplasmic Granules↗
PubMed1977

Leukokeratosis nicotina glossi-smokers' tongue.

"Leukokeratosis nicotina glossi" or "smokers' tongue" is a homogeneous leukoplakia with evenly distributed pin-point hemispherical depressions. Histologically, there is a loss of glossal papillae, hyperkeratosis, acanthosis and the formation of large drop-shaped rete pegs with central clefting and occasional parakeratotic plugging. Mitotic activity and atypia are not marked and there is no evidence of Candida species infection. In some respects the lesion histologically resembles verrucous carcinoma but, unlike that condition, papillomatosis is not clinically noticeable and an invasive "leading edge" is not apparent. All but one of the subjects in which the lesion was seen were men, all had concurrent leukokeratosis nicotina palati and two gave histories of laryngeal carcinoma.

Adult↗
PubMed1977

Focal epithelial hyperplasia in a group of South Africans: Its ultrastructural features.

Electron microscopic observation of samples of tissues from lesions diagnosed as focal epithelial hyperplasia revealed the presence of viral particles in six (possibly seven) of 13 cases examined. Viral particles were intranuclear and varied from sparsely scattered to densely packed. A crystalline arrangement was present in one case. The chromatin of affected cells was typically condensed into clumps and thick bands, and the nuclear membrane was usually absent in pronounced cases. The nuclei of the basal and prickle cells were frequently indented and the chromatin peripherally condensed. Numbers of lysosomal-like organelles were observed in many of these cells. The ballooning epithelial cells with their mitosis-like aberrations observed with light microscopy consisted of a rim of tonofilaments and organelles and a homogeneous granular center interspersed with dense areas. It is suggested that the nuclear characteristics and numerous lysosomes observed in basal and prickle cells are cellular changes induced by the viral infection and that the mitosis-like aberrations represent a bizarre and arrested form of mitosis.

Cell Nucleus↗
PubMed1975

[Clinical characteristics and genetic identity of the basal cell nevus syndrome (Gorlin-Goltz syndrome)].

The clinical, genetic, radiological, dental and dermatological aspects of 3 patients with the autosomal dominant basal cell naevus syndrome are reported. An analysis of the phenotypic features of 72 cases described in the literature is presented and compared with a previous analysis. Ash leaf hypopigmentation similar to that found in tuberous sclerosis represents a unique finding in this syndrome. Other similarities to the phacomatoses are discussed. We were able to support a previous report that patients with the basal cell naevus syndrome have a normal end-organ response to parathormone stimulation, and that it is most probably not related to pseudohypoparathyroidism, as earlier reports suggested.

Adult↗