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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
PubMed1992

A model for epithelial growth and epithelium-connective tissue interaction studies.

The aim of this study was to evaluate implanted ectocervical biopsy material as a model for morphological studies of normal and abnormal epithelial growth and epithelial-connective tissue interactions. Forty-five specimens were implanted in the flanks of nude (immunodeficient) mice and harvested at 1, 2, 3 and 6 weeks. Superficial necrosis of the epithelial layer with retention of parts of the basal cell layer were evident at 1 and 2 weeks. At 2 weeks granulation tissue enclosed the bases of the implants. Regrowth of epithelium on the surfaces and from the edges of the specimens was seen at 3 weeks. At 6 weeks the specimens were revascularized and the majority coated with a well developed unkeratinized stratified squamous epithelial layer resembling the epithelium of the ectocervix. It is concluded that specimens of human ectocervix, implanted in nude mice, offer the possibility for morphological studies of normal and abnormal epithelial growth and, if experimental difficulties can be overcome, of the epithelial-connective tissue interactions.

Animals↗
PubMed1992

Growth interaction between Candida albicans and Streptococcus salivarius: in vitro and in vivo studies.

Suppression of Candida albicans in the mouth by oral flora has been proposed as one of the mechanisms preventing candidal overgrowth. According to Liljemark and Gibbons (1973), Streptococcus salivarius plays a significant role in this process. The aim of this investigation was to study the growth interaction between C. albicans and S. salivarius in vitro and in vivo. An aerobic continuous-flow system was used for the in vitro study. Pure and mixed cultures of C. albicans (NCPF 3118) and S. salivarius (NCTC 8618) were inoculated into a buffered medium containing either 0.1 per cent or 0.001 per cent glucose concentrations and incubated at 37 degrees C for 55 hours. Two in vivo investigations were undertaken using inbred germfree C3H mice. In the first, mice were exposed to a mixed suspension of S. salivarius and C. albicans for 48 hours. In the second the mice were exposed to S. salivarius for 48 hours. Fourteen days later they were contaminated with C. albicans. A comparison of growth curves showed no growth inhibition between the species. The in vivo studies showed that oral lesions from candidal infestation occurred in all mice. We were therefore unable to demonstrate in vitro or in vivo suppression of C. albicans in the presence of S. salivarius.

Animals↗
PubMed1991

Human papillomavirus (HPV) DNA in focal epithelial hyperplasia by in situ hybridization.

Eighteen cases of focal epithelial hyperplasia (FEH) were investigated for the presence of human papillomavirus (HPV) group specific antigen by immunocytochemistry and HPV types 1, 6, 11, 13, 16, 18 and 32 by DNA in situ hybridization employing biotinylated probes. Seven (39%) specimens demonstrated the presence of HPV group specific antigen. Fifteen (83%) specimens were positive for HPV DNA: 9 (60%) showed HPV 32, of which 6 were on non-keratinized mucosa and 3 on border of keratinized and non-keratinized mucosa; 5 (33%) showed HPV 13, 4 lesions on keratinized mucosa and 1 on non-keratinized mucosa; 1 (7%) specimen on non-keratinized mucosa showed HPV-11 related. Two specimens on different sites from one patient showed the same HPV type and one patient had, in addition to FEH, a squamous papilloma also demonstrating the same HPV type. Results show a specific HPV distribution pattern in the epithelium indicating areas of high viral concentration adjacent to areas of low or no viral concentration. This study also indicates the possibility of tissue-site specificity or a latent infection and the possibility of a yet unidentified HPV type associated with FEH. It is suggested that future monitoring of patients be carried out with special reference to HPV type and anatomical distribution pattern for FEH lesions.

Adolescent↗
PubMed1990

Collagen in submucous fibrosis: an electron-microscopic study.

A comparison of the electron-microscopic features of 11 examples of submucous fibrosis in its moderately advanced and advanced stages with 15 control specimens revealed no obvious abnormality of the collagen fibrils. The notable feature of the collagen in this disease is the densely packed bundles in the lamina propria, reaching close to the epithelial-connective tissue junction, to blood vessel walls, salivary glands and muscle fibers. The width and the periodicity of fibrils vary in both groups of specimens, noticeably so, next to the junction and close to blood vessels, salivary glands and muscles. This is due to the presence of the thinner Type III collagen fibrils in these sites and the natural variation of Type I fibrils. Immunofluorescent microscopy and special staining with sirius red and polarization microscopy demonstrate both types, confirming that Type I collagen forms the bulk of the collagen and that Type III is localized in the sites mentioned above. It is concluded that although there is an excessive increase of collagen, especially Type I, in submucous fibrosis, the fibrils are still morphologically normal.

Collagen↗
PubMed1990

A grave matter--dental findings of people buried in the 19th and 20th centuries.

The exhumed remains of 181 people, buried during the period 1848-1984 were examined. Because of the carelessness of exhumations, only 125 yielded sufficient information to compare the condition of skulls and jaws with the period in the grave, while 63 yielded information about the teeth. No correlation could be shown between the condition of the skulls and jaws and the period interred, but it was found that the better preserved remains belonged to younger people. Dental findings included the presence of healthy and decayed teeth, gold foil restorations, gold and porcelain inlays, amalgam and silicate fillings, and vulcanite and acrylic dentures. Amalgam restorations were present in people buried from 1875 (114 years ago) and vulcanite dentures from 1882 (107 years ago). The characteristics of the earliest amalgam restorations showed that they could have been placed before 1850. Findings of this study indicate that: (a) one cannot on the appearance of exhumed remains estimate the burial period, (b) dental features were well preserved and can be used for dental identification if antimortem data are available, (c) advanced dentistry could have been practised in South Africa during the last century, and (d) recovery of human skeletal remains from old cemeteries should be undertaken with care to preserve as much information as possible. A plea is made for closer co-operation between developers of old graveyard sites and scientists in order to preserve as much information as possible.

Burial↗
PubMed1989

Postmortem pink teeth. Histochemical identification of the causative pigment.

The phenomenon of postmortem pink teeth has been reported in subjects who have died suddenly and unnaturally, and whose bodies have been subsequently exposed to a wet or moist environment. Ground and EDTA-decalcified sections of teeth of 21 corpses exhibiting postmortem pink-stained teeth were investigated for the identification of the responsible pigment. With histochemical methods and ultraviolet microscopy, the causative pigment was identified as undegraded hemoglobin. Staining from hemosiderin, bile and bile-related pigments, and porphyrins was ruled out. However, histochemical techniques are unable to reveal the form in which the hemoglobin occurred. The cause of death or time of death had no observable effect on the staining reactions for hemoglobin in the teeth.

Burns↗
PubMed1988

Betel-nut chewing and submucous fibrosis in Durban.

A stratified random sample among South African Indians living in Durban revealed the occurrence of betel-nut chewing and the resultant submucous fibrosis (SF) to be relatively high. Women chewers predominated in a ratio of 13:1. The habit increased with age and 30.6% of women over 65 years practised the custom. Thirty-eight per cent of chewers revealed signs of impending and established SF; women predominated 70:1, and the majority of sufferers in this instance belonged to the age group 45-54 years (12.9%). Forty-six per cent of those with signs associated with SF had fibrous bands in the mouth and were regarded as having established SF. It was calculated that 5% of the total Indian population in South Africa could be chewers and that 2.3% may develop SF.

Adolescent↗
PubMed1988

Betel chewing and dietary habits of chewers without and with submucous fibrosis and with concomitant oral cancer.

The betel-nut chewing habit and the intake of chillies in the diet were analysed in 178 chewers identified during a stratified random survey and in 124 hospital patients suffering from submucous fibrosis (SF). There were no signs or symptoms of SF in 115 chewers from the survey; the remaining 63 exhibited features of impending and established SF. Of the 124 hospital patients, 10 also had oral cancer. Subjects suffering from SF had practised the habit in whatever form for a significantly shorter period than chewers without SF and belonged to a significantly younger age group. A significantly larger proportion of this group preferred the boiled nut by itself and not as part of the betel package (paan or pan). No relationship could be established between SF and the use of tobacco, lime or chillies. There was no difference in frequency of the habit between chewers without SF and chewers with SF. The 10 oral cancer patients all had moderately to well-differentiated squamous carcinomas arising in the buccal sulci (8), the soft palate (1) and upper oesophagus (1). Eight had cancer on presentation and 2 developed the tumour while under observation. Nine chewed the nut only and only 1 preferred paan which included tobacco, lime and catechu, which is contrary to the proposal that tobacco or lime are the carcinogens. It is concluded that a relationship between betel-nut chewing and SF exists but the mechanism by which the disease develops is still obscure. A genetic predisposition may be important.

Adolescent↗
PubMed1988

Hypohidrotic ectodermal dysplasia: a genealogic, stereomicroscope, and scanning electron microscope study.

This is a report of three patients with hypohidrotic ectodermal dysplasia, or Christ-Siemens-Touraine syndrome, their genealogic backgrounds and the stereomicroscope and scanning electron microscopic appearances of the hair, the skin of their fingertips and palms as well as skin studies of members of their families. The skin morphology was recorded by means of silicone monomer rubber impressions and epoxy resin dyes. In two of the patients the disease was acquired by X-linked inheritance, while in the third, a boy, it appeared to follow an autosomal dominant pattern. Defects of the skin of the fingertips and palms of the propositi and members of the families included abnormalities of the morphology and pattern of the epidermal ridges, reduction of sweat pores varying from 13 to 87% of normal, and changed anatomy of the openings of the sweat glands. The openings were shallow and with less whorling compared to the normal, funnel-shaped sweat pores. Among the sweat pores, micropores, or openings with an average diameter of 5.3 micrometers, were observed. One of the propositi and the affected father of another had orifices on their fingertips resembling hair sheaths. Two propositi and the affected father of one exhibited grooving of the hair. The findings confirm the necessity for genealogic investigations in patients with or suspected of having the disease in order to advise parents or prospective parents. They also illustrate the usefulness of stereomicroscopy and scanning electron microscopy in observing skin and hair abnormalities.

Child↗
PubMed1988

Postmortem pink teeth: in vitro production.

The aim of this study was to produce pink teeth experimentally with cadaver blood and to correlate the time sequence of the coloration with the pattern of hemolysis of the blood. The blood from 7 cadavers (postmortem period 8-58 h) was used to stain 7 groups of 14 teeth each. All the teeth were divided longitudinally and one half received blood which contained a piece of skin (to imitate pulpal autolysis) and the other half cadaver blood only. Circumpulpal discoloration commenced on the sixth day postmortem and increased to 18 days. At 6 days, hemolysis was evident histologically and the separation between plasma and blood cells had disappeared in centrifuged blood. No difference was noticed between the blood with and without skin. It is concluded that pink staining of teeth can only occur after hemolysis and that discoloration becomes obvious macroscopically at about 6 days.

Dental Pulp Necrosis↗
PubMed1988

Submucous fibrosis (SF) in ex-betel nut chewers: a report of 14 cases.

The clinical and histological features are described of 14 subjects with SF who had given up betel nut chewing. The typical clinical features of the disease: blanching of the mucosa, palpable fibrous bands and complaints of burning and dryness of the mouth were still present, even in subjects who had not practised the habit for as long as 13 years. The characteristic histological features of the disease: atrophy of the oral epithelium and extensive fibrosis of the lamina propria, which in some instances penetrated into the submucosa, also persisted.

Adult↗
PubMed1988

Submucous fibrosis in non-betel nut chewing subjects.

Six patients with the typical features of submucous fibrosis (SF) but without a history of betel nut chewing or an abnormal intake of chillies are described. All had palpable fibrous bands in their mouths and limited mouth opening as well as a variety of symptoms associated with SF. Biopsy specimens of the cheeks showed the classic features of SF, an atrophic epithelium and a very dense lamina propria. Also seen were hyperkeratosis, atypia and signet cell-like degeneration of the epithelium and chronic inflammation of the lamina propria. In 3 cases the fibrosis extended into the submucosa. As no reason for the disease could be demonstrated the question is asked whether people with a genetic predisposition can develop SF spontaneously.

Adult↗