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Biomedical subjects

N W Johnson

Publications and source records attributed to N W Johnson.

At least 55 records · Page 3Linked to original sources
PubMed1999

Dentists and oral cancer prevention in the UK: opinions, attitudes and practices to screening for mucosal lesions and to counselling patients on tobacco and alcohol use: baseline data from 1991.

OBJECTIVE: To investigate the opinions, attitudes and practices towards oral cancer prevention among UK dentists as a baseline from which to measure the need for continuing education efforts in this area. DESIGN AND METHOD: Postal questionnaire survey carried out in August 1991. A questionnaire with 13 test items was piloted at continuing education courses then distributed to all subscribers of the British Dental Journal with a postage paid return envelope. The aspects inquired into were recent attempts by dentists at updating their knowledge on oral cancer, their practical approaches to screening for oral mucosal diseases and follow-up actions after oral screening, their questions to patients regarding the major risk factors for oral cancer, their efforts towards behavioural counselling for patients and any constraints felt or experienced in this regard. RESULTS: The questionnaire was circulated to 15,836 dentists. The response rate of 16% was poor but due to the many dentists circulated, 2519 responses were available for analysis. This large sample, though presumptively biased towards those interested in professional matters, showed an encouraging 84% claiming to perform screening of the oral mucosa routinely. Among these, 74% reported referral of screen detected cases to a hospital for further attention and only 4% would adopt a wait and see policy. Disturbingly, half of the respondents did not enquire about risk habits related to oral cancer and, among the other half who claimed to make such enquiries, only 30% routinely provided brief health education advice concerning these. Seventy-one percent agreed that giving advice against tobacco use is desirable but major constraints were identified, notably a lack of training, and frustration regarding patient compliance. There was even greater reluctance on the part of the respondents to enquire into the alcohol use of their patients and to provide advice on alcohol moderation. CONCLUSIONS: Most of this large but unrepresentative sample of UK dentists were carrying out screening of the oral mucosa as a part of their prevention activities in 1991. However, the survey indicated a considerable need for improvement in the manner and extent of provision of health advice in respect of the major risk factors for oral cancer: such a substantial need amongst the presumptively better motivated implies that the need amongst the practitioner population at large is even greater.

Alcohol Drinking↗
PubMed1999

Guidelines for the use of antimicrobial agents to minimise development of resistance.

There is currently worldwide concern about the problems of antimicrobial resistance. A number of important bodies such as the World Health Organisation and the British House of Lords have identified the reasons for the emergence of resistance to antimicrobial agents and the preventive measures which need to be urgently implemented to curb the spread of resistant organisms. The reasons for the emergence of resistant organisms are not difficult to find. During the past half-century, since the discovery of penicillin by Fleming, people in both the developing and the developed world have accepted antimicrobial agents as a fundamental right, not only to demand at the first sign of a trivial infection but also to self prescribe with readily available, cheap antimicrobial agents. Such unbridled abuse of antimicrobial agents not only in man but also in animals could lead down a slippery slope to an era where the microbe may rule supreme once again. Indeed some authorities are forecasting a 'post-antibiotic era' (as opposed to the pre-antibiotic era before the discovery of penicillin) in the foreseeable future when many infectious diseases will once again be almost impossible to treat.

Animals↗
PubMed1999

Option-4 algorithm for third generation disc probe: agreement of selected site-specific relative attachment level measurements and detection of longitudinal site-specific attachment level change.

BACKGROUND: Longitudinal site-specific attachment level change (SSAC), identified from serial relative attachment level measurements (RAL), is the principal indicator of progression/regression of periodontal diseases. Many variables confound RAL reproducibility and affect measurement error. The Option-4 algorithm was designed to reduce measurement error and improve accuracy and sensitivity of SSAC detection. The study aimed to evaluate the performance of the Option-4 algorithm. METHODS: A precalibrated clinician recorded full mouth RAL with a third generation disc probe on 4 occasions over 6 months in 16 subjects (mean age 48.1 years) with moderately advanced chronic adult periodontitis (2,312 sites). Option-4 allowed up to 4 RAL recordings per site per visit until 2 values had differences < or =1.0 mm and their mean was < or =1.0 mm from the previous visit mean: the clinician made the selection if these criteria were unfulfilled. RESULTS: Within-visit agreement < or =1.0 mm was > or =99.6%: all within-visit correlation coefficients = 0.98 (P<0.001). At each visit, mean difference in Option-4 values was < 0.05 mm, mean absolute difference (ignoring direction) was < or =.34 mm. Mean site-specific variances ranged from 0.092 mm2 to 0.097 mm2 across all visits. Subject thresholds for site-specific attachment level change (from estimated 95% confidence limits of visit 1 data) ranged from 0.52 mm to 0.67 mm. Linear SSAC (by linear regression) and between-visit patterns of SSAC were investigated. SSAC was detected in 100% subjects and at 51.0% measured sites. Linear SSAC (R2 > or =0.90: P < or =0.05) occurred at 105 sites (4.5%): 32 sites (1.4%) deteriorated, 73 sites (3.1%) improved. Between-visit SSAC occurred at 1,074 sites (46.5%): 391 sites (16.9%) deteriorated, 295 sites (12.8%) improved, and 388 sites (16.8%) showed exacerbation/remission patterns. CONCLUSIONS: The Option-4 algorithm produced high RAL agreement. Site-specific attachment level change was detected in both directions in 100% subjects and at 51.0% measured sites.

Adult↗
PubMed1999

Site-specific attachment level change detected by physical probing in untreated chronic adult periodontitis: review of studies 1982-1997.

BACKGROUND: Site-specific attachment level change, detected from sequential physical probing measurements, is currently the most common method of determining the progression/regression or stability of disease status in subjects with chronic adult periodontitis. The sensitivity and accuracy of detection is dependent on the type of probe used, the recording method, the measurement error, and the method of data analysis. In recent years, there has been world-wide interest in developing instruments and methods to minimize measurement error. Published data report disturbingly wide variation in the prevalences and rates of site-specific attachment level change which are difficult to reconcile with biological likelihood. The present paper aims to summarize the salient points from the key studies and to compare the results. METHODS: The literature between 1982 and 1997 was reviewed for studies in which site-specific attachment level change was detected by physical probing methods in patients with chronic adult periodontitis. RESULTS: The review documents 23 studies by probe generation, compares methods and results and summarizes the results according to the thresholds and probe type used. The 23 studies used an array of probe types from the 3 probe generations. CONCLUSIONS: From this review, we conclude that: 1) There are surprisingly few papers which have addressed the question of site-specific attachment level change in untreated chronic adult periodontitis. 2) There are considerable differences in the probes used, in the thresholds achieved, in the number of measurements taken, in the number of subjects and sites studied, and in the duration of the studies. Valid comparisons between studies are, therefore, rarely possible. 3) Only 8 out of 23 papers from 1982 to 1997 have adequate data. Most papers report only losing sites and therefore ignore many of the measurements recorded. Only one paper describes losing sites, gaining sites, and sites showing exacerbation/remission patterns of change. 4) The range of changes described show such variation that it has to be concluded that we cannot reliably detect site-specific attachment level change by physical probing and thus, at the end of the 20th century, we have no clear idea of the natural history of this disease.

Adult↗
PubMed1999

Knowledge, attitudes and beliefs of adult South Asians living in London regarding risk factors and signs for oral cancer.

BACKGROUND: South Asian communities in the UK are thought to be a high-risk group for oral cancer, primarily because of betel-quid (pan) chewing habits. However there has been little research on the communities' perception of oral cancer. AIM: This investigation was undertaken to assess the knowledge, attitudes and beliefs of South Asian adults (n = 367) regarding the risk factors and signs for oral cancer. DESIGN AND SETTING: The information was obtained by means of a self-administered questionnaire and structured interviews at six Asian community centres and three general medical practices in north west London. PARTICIPANTS: Subjects ranged in age from 16 to 80 years and came from diverse socio-economic and cultural backgrounds. RESULTS: Tobacco use was the only risk factor correctly identified by most adults (82%). A significant difference (P < 0.001) was seen in betel-quid chewing habit among the age groups with 42.2% of adults in the 50-80 year age group practising this habit as compared to only 5.3% in the 16-29 year age group. Another finding was that the traditional method of betel-quid chewing is being replaced with readily available processed areca nut and tobacco products. CONCLUSIONS: There is extensive misinformation and a general lack of awareness about the risk factors and signs of oral cancer among the South Asian communities irrespective of age, gender, South Asian subgroup and social class. It is clear that betel-quid chewing is a common habit among the population and especially in the elderly population. It is recommended that health promotion advice be targeted to this population and their carers.

Adolescent↗
PubMed1998

A smoking cessation programme conducted through dental practices in the UK.

OBJECTIVES: To assess the feasibility of using primary care dentists and the dental team providing smoking cessation advice in practice. DESIGN: A prospective study to examine the success of a smoking cessation programme. SETTING: 54 primary care dental practices in the UK. METHOD: Training and educational materials were supplied to members of the dental team and to potential recruits smoking 10 or more cigarettes a day. Recruitment was over 6 months and subjects were followed up for 9 months. In addition to dentists' counselling, nicotine patches were made available, on request, at cost price. Salivary cotinine assay was used for validation of smoking levels at initial counselling and 9 months after recruitment. RESULTS: 54 practices were enrolled but only 22 recruited patients. Records of 154 eligible patients were evaluated. Compliance to attend follow up clinics was poor--only 74 reported at 9 months. Among them 17 (11%) were successful in giving-up tobacco for 9 months as validated by patient histories and salivary cotinine assay. A large variation performance of the dental practices was noted. CONCLUSIONS: Motivated dentists with staff support and access to information on smoking counselling are able to contribute to tobacco control measures in the community. The success of this programme closely parallels those reported in general medical practice settings. In view of the very considerable attrition rates found at all levels of the programme in the present study and the uneven performance of the participating practices the quit rate reported here may not accurately reflect what could be achieved in an individual primary care setting.

Adult↗
PubMed1998

Diversity of naturally occurring Epstein-Barr virus revealed by nucleotide sequence polymorphism in hypervariable domains in the BamHI K and N subgenomic regions.

The extent of nucleotide sequence microheterogeneity varies among subgenomic regions of Epstein-Barr virus (EBV). We examined, in EBV-carrying lymphoid cell lines, the extent of polymorphism in EBV DNA fragments amplified from the BamHI E, K, N and Z regions, and then investigated the diversity of the more hypervariable regions in tissues and body fluids. In cell lines, sequence dissimilarities in a genotype-specifying fragment of the EBNA-3C gene varied from < 1-4% within each genotype; dissimilarities in the first intron of the BZLF- 1 gene were < 2% within each genotype. By contrast, dissimilarities in a C-terminal unique domain of the EBNA-1 gene, and in a fragment that encompasses and is upstream of the LMP-1 start codon, varied between 2 and 7% and were not genotype-specific. The sequence diversity in BamHI K and N regions was then examined in tissues and body fluids by single-strand conformation polymorphism (SSCP) analysis and cycle sequencing. Extensive inter-host diversity was observed, whether the host was co-infected by human immunodeficiency virus (HIV) or not. In the oral cavity of HIV-infected patients, inter-compartmental EBV diversity could be demonstrated, even between sites that were anatomically proximate. Studies of BamHI K clones derived from EBV in oral lesions revealed infection by multiple variants. Identification of hypermutable loci within the EBV genome such as those located in the BamHI K and N regions should permit fine discrimination of individual EBV variants.

Amino Acid Sequence↗
PubMed1998

A comparison of the management of potentially malignant oral mucosal lesions by oral medicine practitioners and oral & maxillofacial surgeons in the UK.

This study describes the results of a survey undertaken to assess the management of potentially malignant oral mucosal lesions by oral medicine practitioners and compares their approach with that of oral & maxillofacial surgeons that we have previously described. Significant differences were noted between the two groups in the use of photography to document the lesions and in the use of certain special investigations, which included measurement of serum iron, serum ferritin, serum Vit B12, red cell folate and candidal isolation. The groups also varied in the perceived importance of the age of the patient and anatomical site of the lesion when deciding on the need for further biopsy. There was also significant variation in the use of certain treatment modalities, including excising non-dysplastic and severely dysplastic/carcinoma in-situ lesions and eliminating trauma when treating mild/moderately dysplastic and severely dysplastic/carcinoma in-situ lesions. Significant differences in the frequency and duration of follow-up were noted for non-dysplastic lesions. Finally, the two groups differed significantly when asked to rank the perceived importance of certain factors (the histopathology of the most recent biopsy and the anatomical site of the lesion) when deciding the need to follow-up. Possible reasons for the variation are discussed.

Age Factors↗
PubMed1998

Characterization of an amorphous deposit in the lamina propria in oral snuff users in the Sudan as collagen.

Histological and ultrastructural features of 25 oral snuff dipper's lesions with distinctive subepithelial hyaline deposits were investigated. Periodic acid-Schiff reaction with and without diastase digestion demonstrated the presence of glycogen and other carbohydrates, but histochemical stains for normal collagen, elastin and fibrin showed a weak variable reactivity of the deposit. Although in 7/25 cases the deposit was in close proximity to labial salivary glands and on occasions ducts were found within the deposit, the presence of mucin was not a consistent feature. Congo red staining and immunohistochemical investigation with an anti-amyloid antibody did not support the previous contention that such deposits were amyloid in nature. Immunohistochemically, collagen antibodies also provided negative results, but ultrastructural features of three biopsies studied suggest that the bulk of this deposit is made up of collagen, as typical cross-striated fibrils were found. The pathogenesis of this deposit could therefore be interpreted as over-production and/or reduced turnover of collagen by resident fibroblasts, which is further altered by the ingredients of toombak. The deposit does not appear to be a secretory product.

Adult↗
PubMed1998

p53 expression in oral precancer as a marker for malignant potential.

The potential of p53 protein expression as a marker for determining which oral precancerous lesions may transform to malignancy with time was assessed. We compared the p53 expression in archival formalin-fixed, paraffin-embedded tissues from 22 baseline biopsies of precancerous lesions that transformed to cancer in 4-25 years against that in 68 similar lesions that did not transform over the same time period. Twenty-nine percent of precancers that transformed were p53-positive at baseline, compared to 31% of the biopsies that did not transform to malignancy. When examined by immunohistochemical methods p53 expression failed to detect potential malignant status of oral precancer. Non-specificity of the assay may account for this result but overexpression of p53 due to DNA damage by tobacco/betel-quid in non-progressive lesions needs further study. Nine precancerous lesions became p53-immunoreactive from precancer to cancer. This may suggest p53 overexpression peaks close to the time of transition from precancer to cancer rather than early in the natural history of oral precancer.

Areca↗
PubMed1998

Relationship of p53 overexpression to other cell cycle regulatory proteins in oral squamous cell carcinoma.

Aberrations of the p53 gene and the overexpression of its protein are described in a variety of neoplasms, including oral and other head and neck cancers. Here we report the association of p53 (over)expression with a downstream cell cycle inhibitor p21/waf 1 in oral squamous cell carcinoma (SCC). The loss of expression of p16 and p27, two other cyclin-dependent kinase (cdk) inhibitors, was also examined. In this panel of tumours, 10/24 carcinomas were p53-immunopositive. Heterogeneous expression of p21 and p27 was seen in 10/24 SCC and 9/16 SCC, respectively, and this was not correlated to p53 status. The expression of p21 and p27 in these SCCs suggests the existence of mechanisms by which some growing tumour cells may tolerate these cell cycle inhibitors; eight SCCs lacked expression of both inhibitors but only two of these cancers overexpressed p53, suggesting that accumulation of p21/p27 can be independent of the functional status of the p53 gene. Data do not support a clear example of a phenotype that shows an overexpression of p53 with downregulation of p21 or p27 leading to cell cycle alterations. Furthermore, only three SCCs were p16-negative and p53-positive. This suggests that these two tumour suppressors may act in separate pathways.

Adult↗
PubMed1998

p53 aberrations in oral submucous fibrosis and oral squamous cell carcinoma detected by immunocytochemistry and PCR-SSCP.

An archival series of oral biopsies from Karachi, Pakistan, consisting of 21 cases of oral submucous fibrosis (OSF) and 27 cases of squamous cell carcinoma (SCC), of which 6 had arisen from OSF, were used to examine the aberrations in the structure and expression of the p53 tumour suppressor gene. The PCR-SSCP method was used for mutation analysis of exons 2-9, and (over)expression of p53 protein was detected by immunocytochemistry using monoclonal antibody DO 7. Positive immunostaining was observed in 15/20 (75%) of OSF specimens, 3/6 (50%) of SCC arising from OSF and 14/21 (67%) of SCC not arising from OSF. Mobility shifts in SSCP indicative of a mutation in p53 or loss of heterozygosity (deletion of a band) were seen in 13/21 cases of OSF and 15/27 cases of SCC. There was concordance between immunocytochemistry and SSCP results in a majority (33/48) of samples. Though the number of analysed SCC cases arising from OSF was limited, the results suggest that p53 mutation/protein stabilisation may play a part in the pathogenesis of OSF and its progression to SCC.

Adolescent↗
PubMed1998

Microbial contamination of dental unit waterlines: the scientific argument.

The quality of dental unit water is of considerable importance since patients and dental staff are regularly exposed to water and aerosols generated from the dental unit. The unique feature of dental chair water lines is the capacity for rapid development of a biofilm on the dental water supply lines combined with the generation of potentially contaminated aerosols. The biofilm, which is derived from bacteria in the incoming water and is intrinsically resistant to most biocides, then becomes the primary reservoir for continued contamination of the system. Dental water may become heavily contaminated with opportunistic respiratory pathogens such as Legionella and Mycobacterium spp. The significance of such exposure to patients and the dental team is discussed. There is at the present time, no evidence of a widespread public health problem from exposure to dental unit water. Nevertheless, the goal of infection control is to minimise the risk from exposure to potential pathogens and to create a safe working environment in which to treat patients. This paper evaluates the range of currently available infection control methods and prevention strategies which are designed to reduce the impact of the biofilm on dental water contamination, and are suitable for use in general practice. Bacterial load in dental unit water can be kept at or below recommended guidelines for drinking water (less than 200 colony forming units/ml) using a combination of readily available measures and strict adherence to maintenance protocols. Sterile water should be employed for all surgical treatments.

Aerosols↗
PubMed1998

A survey of consultants treating upper aerodigestive tract cancer in the UK.

A study was undertaken to determine the current service provision for the treatment of upper aerodigestive tract (UAT) cancers in the UK. A postal questionnaire was sent to all consultant members of relevant specialist societies, with 1041 (74%) responding. Treatment of UAT cancer is widely dispersed with over 900 consultants from five major disciplines treating, on average, less than 10 cases per year. There were few regional or provider differences in the facilities and services available and in processes used for assessing patients. There is little systematic collection of data for audit or research and some consultants do not record stage. The involvement of other disciplines in the assessment process, use of joint clinics, counselling, specialist nursing and therapy services appears to be low. There is a need for rationalisation of head and neck cancer services; for more systematic collection of data for audit and research and for improvements in the use of joint clinics and support services.

Cancer Care Facilities↗