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Biomedical subjects

H K Williams

Publications and source records attributed to H K Williams.

At least 19 recordsLinked to original sources
PubMed2004

British Society for Oral and Maxillofacial Pathology, UK: minimum curriculum in oral pathology.

This paper describes a minimum curriculum in oral pathology for undergraduate dental education in the United Kingdom prepared by the Teachers Group of The British Society of Oral and Maxillofacial Pathology. Curricular development in UK dental schools is overseen by the General Dental Council (GDC), the Quality Assurance Agency for Higher Education (QAA) and the European Union. These organisations define the framework for education and learning outcomes but provide little or no detailed guidance on syllabus or curriculum. This recommended minimum curriculum has been drawn up by a consensus process involving teachers of oral pathology from all 13 UK and one Irish dental schools and is cross-referenced to the GDC and QAA published requirements for undergraduate dental education.

Curriculum↗
PubMed2000

Juvenile ossifying fibroma. An analysis of eight cases and a comparison with other fibro-osseous lesions.

Juvenile ossifying fibroma (JOF) is a well-defined clinical and histological entity that has recently been separated from other fibro-osseous lesions, including cemento-ossifying fibromas. Its biological behaviour is well defined, but unexplained. Its behaviour, clinical and histological appearance, however, bears resemblance to osteofibrous dysplasia of long bones, a lesion that in some cases has been reported to be part of a spectrum of diseases associated with adamantinoma, thus accounting for its variable biological behaviour. Eight cases of JOF were examined for islands of epithelium or single epithelial cells using immunocytochemistry. While these cases of JOF could clearly be separated from other fibro-osseous lesions, and were histologically similar to osteofibrous dysplasia, the absence of cytokeratin-positive cells in all cases suggests that another reason for its biological behaviour has still to be found.

Adolescent↗
PubMed2000

Chronic sclerosing sialadenitis of the submandibular and parotid glands: a report of a case and review of the literature.

Chronic sclerosing sialadenitis (also known as Küttner tumor) is a chronic inflammatory condition of the salivary glands, first described by Küttner in 1896. Clinically, the disease cannot be distinguished from a true neoplasm. The submandibular gland is affected more commonly than any other salivary gland. This report is of a case of widespread swelling of the salivary glands in which histologic features of chronic sclerosing sialadenitis were seen in the submandibular and parotid glands. The etiology, pathogenesis, and differential diagnosis of this disease and the clinical outcome of this case are discussed and presented.

Aged↗
PubMed2000

Molecular pathogenesis of oral squamous carcinoma.

Oral squamous carcinogenesis is a multistep process in which multiple genetic events occur that alter the normal functions of oncogenes and tumour suppressor genes. This can result in increased production of growth factors or numbers of cell surface receptors, enhanced intracellular messenger messenger signalling, and/or increased production of transcription factors. In combination with the loss of tumour suppressor activity, this leads to a cell phenotype capable of increased cell proliferation, with loss of cell cohesion, and the ability to infiltrate local tissue and spread to distant sites. Recent advances in the understanding of the molecular control of these various pathways will allow more accurate diagnosis and assessment of prognosis, and might lead the way for more novel approaches to treatment and prevention.

Carcinoma, Squamous Cell↗
PubMed1998

Sequential changes in cadherin-catenin expression associated with the progression and heterogeneity of primary oesophageal squamous carcinoma.

Maintenance of an adhesive function for cadherins requires appropriate membranous cellular expression and intact cadherin-catenin complexes. In normal squamous mucosa of the oesophagus there is membranous co-expression of E- and P-cadherin (E-cad, P-cad) in the basal compartment, whereas suprabasal stratification is associated with preservation of E-cad expression but loss of P-cad. Immunohistochemical staining of squamous dysplasia/carcinoma in situ shows a striking increase in the proportion of cells within the epithelial compartment showing co-expression of E- and P-cad with strong appropriate membranous expression of beta and gamma catenin. Strong membranous co-expression of E- and P-cad and beta catenin is seen on keratinocytes at the periphery of islands of invasive better-differentiated squamous carcinoma with keratinisation, mimicking normal mucosa. Beta catenin may be phosphorylated with implied loss of cadherin binding. Membranous cadherin and catenin expression is significantly down-regulated in poorly differentiated squamous carcinoma. No beta catenin mutations were demonstrated in squamous carcinomas following DNA extraction and sequencing, nor was any nuclear cadherin seen. Changes in cadherin-catenin complexes with cellular phenotype is well demonstrated in spindle cell carcinomas with a shift of cadherin expression from membranous to cytoplasmic between the epithelioid and spindle cell components of the tumour and with loss of expression in the sarcomatoid elements. In conclusion, we demonstrate an increased expression of P-cadherin early in tumourigenesis with loss of cadherin-catenin complexes in poorly differentiated invasive carcinomas. Cadherin/catenin expression may govern both the phenotype and biology of oesophageal squamous carcinomas.

Cadherins↗
PubMed1998

Expression of cadherins and catenins in oral epithelial dysplasia and squamous cell carcinoma.

The immunocytochemical expression of cadherins and catenins was examined during the process of oral carcinogenesis by comparing their expression in normal and dysplastic epithelium with primary and metastatic carcinomas. While control epithelium showed normal distribution for P and E cadherin and the catenins, in severe dysplasia P-cadherin was upregulated. In other cases and in carcinoma-in-situ adjacent to infiltrating carcinomas, membranous expression of the cadherins and catenins was reduced or lost. The changes in expression of E-cadherin and the catenins suggest that disruption of the E-cadherin/catenin complex is a late event associated with invasion. In primary carcinomas reduced membranous and cytoplasmic staining were observed for both cadherins and catenins. Abnormal localisation of E-cadherin occurred in the more superficial parts of the better differentiated carcinomas, suggesting abnormality to the E-cadherin complex(es). In contrast, membranous expression of cadherins and catenins was reduced or lost in the deep invasive margin of primary carcinomas and in most poorly differentiated carcinomas. For E-cadherin at least, this reduction appears associated with differentiation, invasion and possibly prognosis. Possible mechanisms involved for changes in expression of the cadherins and associated catenins and areas for further study are discussed.

Cadherins↗
PubMed1997

The use by general dental practitioners of an oral pathology diagnostic service over a 20-year period: the Birmingham Dental Hospital experience.

OBJECTIVE: To investigate the use of an oral pathology service by general dental practitioners over a 20-year period. DESIGN: Retrospective analysis of the number of cases received for histological examination in 1975, 1984 and 1994. SETTING: Birmingham Dental Hospital. SUBJECTS AND METHODS: 1101, 2395 and 3366 specimens were accessed respectively for the three years studied. Number and proportion of specimens received, number and proportion that were hard or soft tissue specimens and the information on the request form were recorded. A comparison was made between the provisional clinical and histological diagnoses. RESULTS: Although the number of specimens accessed increased approximately 3-fold, the number of specimens accessed from general dental practitioners increased 5-fold. The variety of histological categories increased by over 50%, most being soft tissue specimens. The number of correct provisional diagnoses increased steadily but the percentage with inappropriate provisional diagnoses remained the same. Information on request forms steadily improved. CONCLUSIONS: The increased number of specimens received from general dental practitioners over the 20-year period reflects an increased demand for an oral pathology diagnostic service. The referral pattern most likely indicates an increased awareness by general dental practitioners of the need to biopsy lesions arising within the oral cavity.

Biopsy↗
PubMed1997

Parotid gland metastases of two uncommon neoplasms with low metastatic potential.

Oligodendrogliomas are uncommon intracranial glial tumours in which extracranial spread is only rarely reported. Similarly, both intracranial and ocular medulloepitheliomas are also rare, with metastatic spread from the ocular neoplasm being less common than its intracranial counterpart. We report cases of an intracranial oligodendroglioma and an ocular medulloepithelioma both of which metastasised to the parotid gland. To our knowledge these are only the second oligodendroglioma and the third ocular medulloepithelioma to be reported as metastasising to this site.

Adolescent↗
PubMed1997

Oral granular cell tumours: a histological and immunocytochemical study.

In a series of nine cases of intra-oral granular cell tumors (GCTs) an attempt was made, using both histochemical and immunocytochemical methods, to determine whether these tumours show Schwann-cell or neuroendocrine differentiation. Positive immunostaining with protein gene product 9.5 (PGP 9.5), neurone-specific enolase (NSE) and S-100, in contrast to predominantly negative immunostaining in 12 cases of neurilemmoma of the head and neck, and a similar pattern of staining with luxol fast blue to five known neuroendocrine tumours, strongly suggests that granular cell tumors may be neuroendocrine in nature.

Adolescent↗
PubMed1995

Immunocytochemical detection of ornithine decarboxylase (ODC) in paraffin-embedded tissues as a possible prognostic indicator for oral lesions.

Intracellular levels of ornithine decarboxylase (ODC) are raised following mitogenic stimulus and in neoplasia. Because lesions of the oral cavity are often difficult to assess histologically, we have determined the value of immunocytochemical detection of ODC as a prognostic indicator in 74 routinely fixed and paraffin-embedded oral biopsies using peroxidase-antiperoxidase and immunogold-silver staining. The latter proved more sensitive, yielding positive reactions in 32 of 43 oral carcinomas (11/14 well differentiated, 16/21 moderately differentiated and 3/5 poorly differentiated) and 7/11 potentially malignant lesions, compared with 19/45 carcinomas and 1/15 potentially malignant lesions, by peroxidase anti-peroxidase. Hyperplastic lesions (n = 7) and normal non-keratinized buccal mucosa (n = 7) were all negative. Follow-up was possible in 13 of the carcinoma patients. Of 7 positive ODC reactions but clinically node-free at biopsy, 2 died and 2 had recurrences within 3 years, whereas all of 6 with no immunoreactivity were symptom-free after 3-5 years. Immunostaining for ODC may be helpful for the prognostic assessment of routinely processed oral lesions and in choosing treatment.

Animals↗
PubMed1993

Neurilemmoma of the head and neck.

The neurilemmoma is an uncommon tumour of the oral cavity. In this present series of soft tissue neurilemmomas the majority occurred within or around the mouth. Initially these were provisionally diagnosed on clinical appearances and behaviour as commoner benign lesions, including the fibro-epithelial polyp, mucocele and papilloma. On sampling they were found to have the histological features of a neurilemmoma. This suggests that the solitary neurilemmoma occurs more frequently than previously reported and should be included in the differential diagnosis of these more frequent benign lesions occurring in and around the mouth.

Adolescent↗
PubMed1989

Persistent sialadenitis of the minor glands--stomatitis glandularis.

In a recurring lesion on the palate of a 60-year-old male, histological features of a chronic inflammatory disease of the minor salivary glands resembling those found in cheilitis glandularis were found. The similarities between the clinical and histological features of our case and cheilitis glandularis are discussed and the inherent nature of the disease emphasised. We propose the terms persistent sialadenitis of the minor glands or stomatitis glandularis, for this condition.

Humans↗
PubMed1988

Mandibular African histoplasmosis: imitation of neoplasia or giant-cell granuloma?

The lesion reported in this article destroyed much of the right side of the mandible in a 14-year-old boy. Clinically, it resembled Burkitt's lymphoma and was initially treated as such. After correct microscopic diagnosis, the mass regressed with the use of intravenous amphotericin B and surgical reduction. The histologic comparison with giant-cell granuloma is considered.

Adolescent↗
PubMed1987

Mesenchymal chondrosarcoma.

2 cases of this rare tumour in Nigerian subjects is described. Clinical features indicated relatively slow but painful growth, aggravated in 1 case by dental extractions. Radical resection was followed by 6-year survival without recurrence or overt metastasis. Microscopic differential diagnosis is discussed.

Adult↗
PubMed1987

Osteosarcoma of the jaws--a series from Kaduna, Nigeria.

15 primary and one metastatic osteosarcoma of the jaw bones in Nigerians are described. The age range was typical of this tumour; most cases were in the mandible. Clinical and radiographic features were often diagnostic but the microscopic appearances were varied and problematical. No metastases were detected and effective surgical treatment depended upon the degree of spread in soft tissue. Inoperable tumours had infiltrated the pharyngeal and tonsillar area. Some resected cases survived for one year or more.

Adolescent↗
PubMed1987

Primary culture of human oral epithelial cells. Growth requirements and expression of differentiated characteristics.

Epithelial cell cultures were initiated from explants of normal human oral mucosa. Growth parameters, cell type, and degree of maturation/cytodifferentiation were assessed by morphological and surface topographical criteria (light and scanning electron microscopy) together with immunofluorescence studies with a panel of antibodies to cytokeratins and extracellular matrix components. The effects of different media formulations were compared. Whereas stromal cell over-growth soon became apparent in media containing 10% serum, in low serum (0.5%) media containing insulin, hydrocortisone, epidermal growth factor (EGF), and/or cholera toxin (CT), epithelial growth was maintained with minimal or absent stromal cell contamination. Cell proliferation, maturation, and differentiation were modulated by EGF and CT: cultures maintained on EGF showed optimal growth but cells typically displayed only limited differentiation. By contrast, CT promoted considerably more cytodifferentiation but at the expense of proliferative capacity. Both factors together were complementary, resulting in maintenance of cells of a more mature phenotype of high proliferative capacity. Cytokeratins of normal oral epithelium in situ demonstrated characteristic changes in patterns of expression associated with differentiation. In culture, proliferative epithelial cells expressed keratins typical of the basal layer, whereas the most differentiated cells were identified by their strong reactivity with antibodies to epidermal keratins. Less mature cells showed expression of keratins associated with nonstratified epithelia. In cultures maintained with CT but no EGF, there was a tendency for weaker expression of basal type keratins, further suggesting that these cells were maintaining a more differentiated phenotype. Extracellular matrix components (fibronectin, laminin, collagen type IV) were not expressed by any epithelial cells in culture. Irrespective of medium composition, cultures did not survive beyond 100 days (5 or 6 subcultivations) before undergoing an irreversible 'crisis' of growth arrest and onset of degenerative changes.

Adolescent↗