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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

Cultured pulp fibroblasts: are they suitable for in vitro cytotoxicity testing?

The use of cell cultures to test the biocompatibility of dental materials is gaining in importance. Any cytotoxic effects that restorative materials may have will be on the dental pulp and for that reason cultured pulp cells should be the model of choice for biocompatibility testing. The aim of this investigation was to study the growth and morphologic characteristics and toxic response of human pulp lines and to compare these parameters to those of human buccal mucosa fibroblasts. Twenty-one specimens of pulp tissue and six from buccal mucosa were cultured using standard techniques. Six pulp cell lines were cultured successfully as were all six from the buccal mucosa specimens. From these specimens, 12 growth curves were computed. To study the morphology of the cultured cells, they were observed microscopically and classified into three morphological types: slender elongated cells (type I), epithelioid shaped cells (type II) and large stellate cells (type III). Their numbers and proportions were determined for each cell line and compared statistically. To gauge sensitivity to toxic materials, cells were exposed to concentrations of arecoline. An analysis of the growth curves showed no statistical difference between pulp cells and buccal mucosa cells; the slopes of the curves, however, differed significantly between individual cell lines, and these individual differences were greater among pulp cell lines. The morphology of the pulp and mucosa fibroblasts was similar microscopically. There was no significant difference between the number and proportion of the cell types in the two groups, but there were significant differences between the individual cell lines. Pulp cells showed a greater inhibition of growth when exposed to arecoline. Because pulp fibroblasts are difficult to culture, their reported survival rate is poor; due to the differences that exist between individual cell lines, we conclude that pulp cells when used as single cell lines or even pooled may not be ideal for testing biocompatibility, especially if reproducibility is a prerequisite. Any evaluation will require tests on not one, but several cell lines in order to minimize the effect of inter-cell-line differences. Their greater sensitivity to toxic substances, on the other hand, may show that pulp cells could be more sensitive indicators of cytotoxicity.

Adult↗
PubMed1999

Oral mucosal lesions associated with betel quid, areca nut and tobacco chewing habits: consensus from a workshop held in Kuala Lumpur, Malaysia, November 25-27, 1996.

A variety of betel/areca nut/tobacco habits have been reviewed and categorized because of their possible causal association with oral cancer and various oral precancerous lesions and conditions, and on account of their widespread occurrence in different parts of the world. At a recent workshop in Kuala Lumpur it was recommended that "quid" be defined as "a substance, or mixture of substances, placed in the mouth or chewed and remaining in contact with the mucosa, usually containing one or both of the two basic ingredients, tobacco and/or areca nut, in raw or any manufactured or processed form." Clear delineations on contents of the quid (areca nut quid, tobacco quid, and tobacco and areca nut quid) are recommended as absolute criteria with finer subdivisions to be added if necessary. The betel quid refers to any quid wrapped in betel leaf and is therefore a specific variety of quid. The workshop proposed that quid-related lesions should be categorized conceptually into two categories: first, those that are diffusely outlined and second, those localized at the site where a quid is regularly placed. Additional or expanded criteria and guidelines were proposed to define, describe or identify lesions such as chewer's mucosa, areca nut chewer's lesion, oral submucous fibrosis and other quid-related lesions. A new clinical entity, betel-quid lichenoid lesion, was also proposed to describe an oral lichen planus-like lesion associated with the betel quid habit.

Areca↗
PubMed1998

South African oral hygienists: their profile and perception of their profession and career.

The aim of the study was to determine a profile of the oral hygienists in South Africa, their views on the profession, work-place, and the practice of their career, which aspects of the work they enjoy and which are not enjoyable, their opinions on expanding duties for hygienists and which duties should be included, and their perceptions about the status and importance of oral hygienists vis-à-vis other health providers. A questionnaire was sent to every third registered oral hygienist and 47 per cent responded. The majority who responded were in the age group 20 to 39 years, had been in practice for less than 15 years, were married, qualified at the Universities of Pretoria and Stellenbosch, and were employed in traditional practice. The larger proportion worked individually and practised from six to eight hours per day. They were happy with the training they received, believed their job was worthwhile, were satisfied with their careers and enjoyed a cordial relationship with dentists. Motivating, educating, assisting patients and communicating with people were the most enjoyable aspects of practice while procedures associated with the treatment of gingivitis and periodontitis and the poor response of patients to treatment were the least enjoyable. The majority preferred expanded duties for hygienists which should include elementary dentistry, local anaesthesia, minor extractions and emergency treatment and they also desired greater independence. Seventy-eight per cent felt that the public does not know what oral hygiene is. The status and importance of the profession were rated comparable to that of physiotherapists, qualified nurses, radiographers and dental therapists but significantly higher than dental assistants.

Adult↗
PubMed1997

The fibroblast population in oral submucous fibrosis.

The purpose of the investigation was to compare the morphology of fibroblasts cultured from healthy oral mucosa and mucosa of patients with oral submucous fibrosis (OSF) and to collate the occurrence of cell types of similar morphology. Cells cultured from biopsy specimens from the buccal mucosa of six subjects who did not chew the areca nut and six patients with OSF who chewed areca nut were grown according to standard techniques. Ninety cells per cell line were recorded daily for 8 days, classified into types F1, F2 and F3 according to their morphology, and the results statistically analyzed. We found that there was a relative increase of F3 cells in relation to F1 cells in OSF, resulting in the ratio of F3 to F1 cells being significantly larger in OSF than the ratio in the controls. As it has been reported that F3 cells in rat connective tissues produce significantly more collagen types I and III than F1 cells, we concluded that a change of fibroblast population has occurred in OSF and that this relative increase of F3 cells in humans, which could be committed to the production of large quantities of collagen, can be an explanation for the excessive collagen formation in OSF.

Adult↗
PubMed1996

An experimental cyst model established from human unkeratinized vaginal mucosa.

Because of the scarcity of sizeable specimens of normal oral mucosa and the availability of human vaginal mucosa, which resembles the lining mucosa of the mouth, we used the latter to establish a human cyst model. Fragments of vaginal mucosa, removed during corrective procedures, were sutured around 2 mm glass balls and implanted into the flanks of nude mice. Thirty-seven specimens were implanted and 31 harvested after 3, 6, 9 and 12 weeks. At 6 weeks the wall of the implanted cyst consisted of recognizable unkeratinized vaginal mucosa but had not healed completely at the sutured edges. From 9 weeks the cyst cavities were healed and the lumens lined by unkeratinized stratified squamous vaginal epithelium. The enclosing connective tissue had retained the characteristics of the lamina propria of the vaginal mucosa and could be distinguished from mouse tissue.

Animals↗
PubMed1996

The establishment of a community of oral bacteria that controls the growth of Candida albicans in a chemostat.

The purpose of this study was to establish and identify a community of oral bacteria that controls the growth of Candida albicans in the chemostat. The chemostat was operated under glucose-limiting conditions at a dilution rate of 0.05 h-1 and inoculated with a yeast-free suspension of a tongue scraping. After a steady state had been reached, it was inoculated with C. albicans to establish the yeast and determine whether its growth could be contained. The steady-state community comprised the species Streptococcus sanguis, Streptococcus sobrinus, Streptococcus mitis, Lactobacillus casei, Eubacterium saburreum, Veillonella dispar and Fusobacterium nucleatum. Bacteroides gracilus and Haemophilus segnis were also detected but infrequently. Yeast growth was suppressed and yeast cells were lost at the same rate as the theoretical washout rate. It is concluded that this mixed community of oral bacteria can be used to identify the parameters that maintain the equilibrium between oral bacteria and C. albicans in the oral cavity.

Antibiosis↗
PubMed1996

The effect of areca nut on salivary and selected oral microorganisms.

The aim of this study was to investigate the effect on the growth of salivary and selected oral microorganisms of areca nut, aqueous extracts of the nut, its major alkaloid arecoline and the components tannic acid and catechin of its tannin fraction. The antibacterial properties of the above were tested on Streptococcus mutans, Streptococcus salivarius, Candida albicans and Fusobacterium nucleatum and, as a control, Staphylococcus aureus. This was followed by investigating its effect on salivary organisms cultured from the saliva after chewing boiled areca nut. Extracts inhibited the growth of the selected organisms in a concentration dependent manner, baked and boiled nuts being significantly more potent than raw nut. Growth of C. albicans was the least affected by the nut extracts. Tannic acid was strongly antibacterial but not catechin or arecoline. No antibacterial effect could be demonstrated on salivary organisms after chewing the nut for 5 minutes but exposure of saliva to the cud for 1 hour caused a significant depression of bacterial growth. It is concluded that the hydrolysable tannins in the tannin fraction, which include tannic acid, are responsible for the antibacterial properties of the nut and that prolonged intraoral exposure to the nut can suppress bacteria in the mouth.

Analysis of Variance↗
PubMed1996

The effect of baked areca nut extract on the growth of buccal mucosa fibroblasts from healthy non-areca nut chewers.

Oral submucous fibrosis is a serious oral disease associated with the habit of chewing areca nut. The habit is relatively common among South Africans of Indian descent. The aim of this study was to observe the effect on growth of buccal mucosa fibroblasts derived from healthy individuals not practising the areca nut habit when the cells are exposed to nut extract. Fibroblast cell-lines from 6 individuals were grown in medium without extract and medium containing 50 and 100 [symbol: see text] g/ml extract of baked nut for 8 days. Cells not exposed to the nut extract behaved homogeneously. Reaction to the nut extracts, however, was dissimilar. The cells of 5 individuals showed no discernable reaction to the extracts while in one instance, the cells of a healthy adult male with no physical disabilities, showed marked growth inhibition. Thus, the finding indicates that when the effect of the nut or its constituents are tested on cells, it is necessary to use several cell-lines of the same cell type or a cell-line of which the growth parameters are standardized.

Adult↗
PubMed1996

Induced candidosis in mice with artificially established oral flora.

The aim of this study was to gauge the effect of an artificially established flora, unnatural for mice, on the induction of oral candidosis in mice. Four groups of BALB/c mice were compared; conventional Candida albicans-free mice, "germ-free" mice which had been inoculated with Candida-free human saliva, germ-free mice which had been exposed to a cocktail of Streptococcus mitis, S. sobrinus and S. sanguis, and uncontaminated germ-free mice. After exposure to C. albicans via drinking water, the four groups of mice were killed and their oral cavities examined for candidal growth and oral lesions. Conventional mice yielded significantly less candidal growth and exhibited significantly fewer oral lesions than the other three groups. Candidal lesions in the two groups of contaminated germ-free mice were significantly fewer than in the uncontaminated germ-free mice. The latter exhibited extensive candidal lesions with little inflammatory infiltrate. It is concluded that mice with human oral micro-organisms have some resistance against candidal infection albeit at a reduced level, that mice with natural oral flora are highly resistant, and that germ-free mice are extremely susceptible to C. albicans infection.

Animals↗
PubMed1996

Peer-reviewed oral and dental research output in South Africa, 1990-1994.

The aim of this project was to determine the oral and dental research output in South African dental schools over a 5-year period. All refereed research articles emanating from South African dental schools which appeared in peer-reviewed journals during the 5 year period, 1990-1994, and which could be traced, were recorded, scrutinized and classified according to the thrust of the research. During this period the 5 schools published 494 articles, 176 from the University of the Witwatersrand, 145 from the University of Stellenbosch, 85 from the University of Pretoria, 54 from the Medical University of Southern Africa and 34 from the University of the Western Cape. Papers were classified into 22 categories. The majority were produced in oral biology, oral pathology and microbiology and dental materials, followed by pharmacology and anaesthetics, epidemiology, community dentistry, preventive dentistry and prosthetic dentistry. A number of articles featured in the rest of the categories. Fifty-five per cent of manuscripts appeared in overseas journals while the bulk of locally published contributions featured in the Journal of the Dental Association of South Africa. The output of research remained constant over the 5 year period with a slight increase of articles in dental materials. The findings indicate that the South African dental schools may have reached a limit in their capacity to produce peer-reviewed research.

Dental Research↗
PubMed1995

Growth of oral and skin fibroblasts from patients with oral submucous fibrosis.

The purpose of the investigation was to evaluate and compare the proliferation (growth) of mouth fibroblasts and skin fibroblasts from patients with oral submucous fibrosis (OSF). Material comprised fibroblasts from fibrous bands situated in the buccal mucosa and from the inner aspect of the forearm of 8 patients with classic features of OSF as well as fibroblasts from 6 buccal mucosa and 8 skin biopsy specimens from healthy non-areca nut chewing individuals. Cells were cultured for 8 days according to standard techniques. Their growth was monitored daily, under optimal conditions as well as exposure to concentrations of arecoline. The data were analyzed using regression analysis, analysis of variance and the Kruskal-Wallis test. We found no statistically significant differences between the proliferation patterns of oral and skin fibroblasts from patients or between those from patients and controls. The reaction of the cells exposed to concentrations of arecoline was similar; at low concentrations (0.1-10 micrograms/ml) normal growth was maintained, while 100 micrograms/ml inhibited growth. It is concluded that fibroblasts from mouths affected by OSF have proliferation patterns which fall within normal parameters, that the excessive collagen formation in established OSF is not due to increased fibroblast proliferation and that arecoline does not stimulate fibroblast proliferation.

Adolescent↗
PubMed1995

Effect of chilli (Capsicum frutescens) extract on proliferation of oral mucosal fibroblasts.

Various concentrations of chilli extract were tested in 2 stages on the growth of a human buccal mucosa fibroblast cell line. Firstly, concentrations of 25, 75, 150 and 300 micrograms/ml were tested on the cell line for 6 days followed by a repeat which included concentrations of 400 and 500 micrograms/ml. In the latter, cell growth was monitored for 18 days. From day 3 (72 hr) suppression of cell growth was evident with concentrations 300-500 micrograms/ml. Total cell death occurred at 16 days with 300 micrograms/ml and at 6 days with 400-500 micrograms/ml. With the lower concentrations, 25-150 micrograms/ml, the daily counts were lower than the control but the difference was not statistically significant. Growth continued unabated. It is therefore concluded that cytopathic effect of chilli extract to fibroblasts is concentration dependent.

Capsicum↗
PubMed1995

Synovial chondromatosis: Report of a rare surgical problem of the temporomandibular joint.

Synovial chondromatosis of the joint is a rare benign condition characterized by the formation of metaplastic cartilage in the synovium of the joint resulting in numerous attached and unattached osteocartilagenous bodies. It may recur after surgical intervention. For this reason removal of the synovium and the bodies is advocated. This is a report of a case which occurred in the temporomandibular joint which had numerous loose bodies and exhibited features of degenerative joint disease as well. The loose bodies were removed, a high condylar shave performed and the synovium left intact. The patient is still free from joint problems five years later.

Adult↗
PubMed1994

Distribution of procollagen type III, collagen type VI and tenascin in oral submucous fibrosis (OSF).

The distribution of procollagen type III, collagen type VI and tenascin was studied in biopsy specimens from the buccal mucosa of 19 Indian women with confirmed oral submucous fibrosis (OSF) using the immunogold-silver staining technique. Immunohistochemistry revealed a loss of stainable procollagen type III and collagen type VI in the fibrotic zones of oral submucous fibrosis compared to normal oral mucosa. Tenascin was noted only very faintly at the subepithelial basement membrane. The present study showed that procollagen type III and collagen type VI in OSF were expressed in a specific pattern which allows a clear differentiation between fibrotic areas and adjacent apparently normal connective tissue stroma. Loss of procollagen type III, and therefore a probable predominance of collagen type I in collagen fiber bundles, and an almost complete loss of collagen type VI might explain the stiffness of the oral mucosa in patients with OSF. The immunohistochemical findings provided evidence that the process of fibrosis starts in the deeper subepithelial connective tissue stroma and not close to the subepithelial basement membrane. Further studies are required to determine whether OSF is due to increased or altered synthesis and deposition of extracellular matrix proteins, altered fibrolysis or both.

Adult↗
PubMed1994

HLA-antigens in oral submucous fibrosis.

HLA-typing was carried out on 122 areca nut chewers who attended hospitals for complaints unrelated to the habit. The subjects were South Africans of Indian extraction. The study did not include haplotypes. Palpable fibrous bands in the mouth indicated oral submucous fibrosis. The subjects were divided into 4 groups based on specific oral symptoms and signs. Groups A and B were without fibrous bands. Group A (47 subjects) included those with one or no symptoms while group B (28 subjects) suffered from 2 to 7 oral symptoms. Group C (17 subjects) had oral symptoms and represented early or mild oral submucous fibrosis and exhibited at least one discrete palpable fibrous band. Group D (30 subjects) were classic oral submucous fibrosis cases with multiple bands. The high occurrence of oral submucous fibrosis in this study group (39%) is similar to the occurrence in comparable age groups reported earlier in South Africa and is conceivably due to the higher age range of the subjects and their relatively long exposure to the areca nut. We were unable to demonstrate a specific pattern of HLA-antigen frequencies in chewers with or without the disease. Furthermore, there were no differences between the study population and the controls. It is concluded that there is not necessarily a HLA-associated susceptibility in oral submucous fibrosis.

Areca↗
PubMed1994

An unusual variant of keratoameloblastoma.

An unusual case of ameloblastoma which depicts cystic follicles containing orthokeratin, parakeratin, desquamated epithelium and necrotic material with dystrophic calcification is presented. The presence of ameloblast-like cells confirms the diagnosis of an ameloblastoma. However, certain features resembled those of the keratoameloblastoma and others, less convincively, the papilliferous keratoameloblastoma. The extensive keratinisation in this tumour and in the aforementioned neoplasms raises the question whether they represent variants of the acanthomatous ameloblastoma.

Adult↗