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Biomedical subjects

S L Mera

Publications and source records attributed to S L Mera.

At least 19 recordsLinked to original sources
PubMed1998

The role of telomeres in ageing and cancer.

Telomeres are regions of DNA that cap the ends of linear chromosomes. In somatic cells the telomeres shorten progressively with every cell division, reducing the number of tandem repeat sequences. Eventually the chromosomes become unstable and the cell is no longer able to replicate. This represents an inherent biological clock in which the somatic cell has only a finite capacity for division. In contrast, germ cells do not undergo telomeric shortening and have relatively unlimited capacities for cell division. The difference is that germ cells retain the enzyme telomerase which is able to restore the telomere ends that are lost during cell division. Although telomerase activity is absent in most somatic cells, cancer cells acquire the ability to activate the enzyme, ensuring their immortal growth characteristics and selective advantage over normal somatic cells.

Cellular Senescence↗
PubMed1995

Screening for cancer and pre-cancer.

In some countries cervical screening has been established for many years and has had a considerable impact on mortality from invasive cervical cancer. Because of this success, and in view of the continued high incidence and mortality from cancers generally, there is much interest in extending screening for other types of cancer. One example is the more recent introduction of mammographic breast screening in the UK. For other cancers, such as those of the colon, rectum, prostate and ovary, screening is currently confined to demonstration projects. Much of the success of cervical screening is attributable to the fact that abnormalities are detectable at a pre-cancerous stage, and treatment is effective in halting progression to invasive cancer. This is not always the case for most other forms of cancer screening.

Breast Neoplasms↗
PubMed1995

Peptic ulcers and gastric cancer.

It is now believed that a large proportion of peptic ulcers, and possibly some gastric cancers, are initiated by infection with Helicobacter pylori. The natural habitat of this bacterial organism is the stomach, and in some populations its presence is ubiquitous. The mode of transmission of the organism is unclear but is believed to be primarily by the faecal-oral route. With improved living standards in developed countries infection rates, particularly in children, appear to be decreasing. Formerly, a commonly accepted explanation for the production of peptic ulcers was excess acid production. The rationale of treatment was to limit acid production or to protect the surface from damage. These treatments can be very effective, but once the treatment course is stopped the damage is likely to recur. The recognition that most cases of peptic ulcer are probably initiated by H. pylori has resulted in new treatments designed to eradicate the organism. This can be very effective and lead to permanent cure, but currently there are problems concerning response rates and increasing resistance by the organism. Gastric cancers are the result of a sequence of changes, some of which may be initiated by H. pylori. Even if it were possible, the eradication of H. pylori will not completely remove the public health problem of either peptic ulcers or gastric cancer. The rarer adenocarcinoma of the cardia is produced independently of infection by the organism and is increasing in incidence.

Helicobacter Infections↗
PubMed1994

Diet and disease.

Dietary factors are influential in the most important public health problems of Western society. Together, diseases such as coronary heart disease and stroke, cancers, and the effects of osteoporosis constitute the most common causes of disability and death. All of these diseases are multifactorial in their aetiology, but there remains some potential for disease prevention by dietary manipulation. For coronary heart disease and stroke, dietary factors play important roles in modulating blood lipids and their propensity for oxidation. In addition the propensity for thrombosis can be influenced by dietary factors, particularly by the inclusion of fish oils. For cancers, the influence of the diet is less certain, but fats, fibre and antioxidant vitamins and minerals have been most closely scrutinised. In osteoporosis the most important dietary factor is the availability of calcium. This is important both in building peak bone mass and in minimising bone loss later on. There is also some evidence that dietary factors can be helpful in minimising the symptoms of disease. Most notably, the inflammatory process in rheumatoid arthritis can be modified by fish and evening primrose oils, although these effects are relatively mild compared with standard pharmaceutical treatments.

Arthritis, Rheumatoid↗
PubMed1993

Atherosclerosis and coronary heart disease.

Coronary heart disease is the largest cause of morbidity and mortality in the UK. The disease develops by the interaction of a variety of environmental agents in people who may be genetically susceptible. Some of the environmental agents can be favourably altered by adjustments to lifestyle, particularly by stopping smoking, increasing exercise levels and controlling the diet. Coronary heart disease is manifested by a number of symptoms due to the partial or complete occlusion of the coronary arteries by a fibrous plaque. The processes of plaque formation can begin very early on in life and progress through various stages. The process may be initiated by injury to the endothelial lining but can also occur in areas without obvious injury. Diagnosis of coronary heart disease is largely by electrocardiographic measurements and a variety of imaging modalities and laboratory investigations. Treatment centres upon the medical control of the symptoms, or surgical intervention in the form of a coronary bypass operation or by coronary angioplasty.

Arteriosclerosis↗
PubMed1992

Senescence and pathology in ageing.

The life expectancy of people living in the UK has been extended over the last century due to changes in the principal causes of death. Nowadays, people are more likely to die of diseases related to the ageing process rather than the infectious diseases which hitherto were more common causes of death in younger people. Ageing is associated with the degeneration of functional capacity in all parts of the body, and at all levels of organisation from molecules to complete organ systems. These functional changes are referred to as senescence. Both genetic and environmental factors govern senescence, although the precise mechanisms and the extent of their involvement are largely unknown. Senescence changes may themselves be responsible for certain diseases and disabilities associated with old age, or they may be a contributory factor and increase a person's susceptibility to particular diseases. The latter is the case with the most commonly encountered causes of morbidity and mortality today, namely atherosclerosis and cancer.

Aged↗
PubMed1992

Colorectal cancer.

Two current areas of interest regarding colorectal cancer are identification of its genetic and environmental causes, and evaluation of the possibilities of implementing screening programmes for asymptomatic disease in the general population. These issues are addressed in the various studies outlined in this update.

Colorectal Neoplasms↗
PubMed1991

Cervical cancer.

Recent trends in the epidemiology of cervical cancer may have implications for the way in which diagnostic services are provided. The issues addressed in the reports detailed below include the risk factors in cervical cancer, the propensity of premalignant changes to progress to malignancy, and the definition of appropriate target populations for screening.

Cervix Uteri↗
PubMed1991

Breast cancer.

This Biomedical Update contains summaries of a personal selection of articles which have appeared over the last year or so on the subject of breast cancer. The issues addressed are related to breast cancer risk and the use of oral contraceptives and hormone replacement therapy, breast screening, the diagnosis of breast cancer, and various prognostic indicators.

Aged↗
PubMed1991

Aluminium, amyloid, and Alzheimer's disease.

Alzheimer's disease is a degenerative disease characterized by the presence of numerous senile plaques and neurofibrillary tangles, primarily in the cortical areas of the brain. There is no known cause of the disease, although exposure to aluminium has been implicated by epidemiological studies and the finding of aluminium in the cerebral plaques and tangles. There is a genetic predisposition for early-onset disease, and Down's syndrome patients are particularly vulnerable. Many of the plaques contain amyloid, and a gene for amyloid precursor protein has been identified on the long arm of chromosome 21. It is possible that the amyloid plaques arise through over-expression of this gene. Since there is no specific marker for Alzheimer's disease, laboratory investigations are restricted to confirming the disease after the patient has died. Recent immunohistochemical studies have been directed towards showing the relationships between the neurones, senile plaques and neurofibrillary tangles, and the presence of amyloid and filament proteins such as tau, ubiquitin and neurofilaments.

Aged↗
PubMed1987

Elastosis in breast carcinoma: I. Immunohistochemical characterization of elastic fibres.

Elastosis associated with invasive ductal and lobular carcinomas of the breast was examined by tinctorial and immunohistochemical staining methods, enzyme digestion, and electron microscopy. The elastotic material exhibited the tinctorial staining properties of elastic fibres, and the ultrastructural appearances were those of elastic fibres although there was a higher proportion of microfibrils than in normal mature elastic fibres. The elastosis was immunostained by antisera to human fetal elastin, lysozyme and amyloid P component, as in other sites where elastic fibres are found. These findings indicate that immunohistochemically intact elastic fibres are present in the elastosis of breast cancer. They also demonstrate that lysozyme and amyloid P component are co-distributed with elastic fibres in elastosis of breast carcinoma, as distinct components with different susceptibilities to enzyme digestion. The cellular origin of elastosis in breast carcinoma remains uncertain.

Actin Cytoskeleton↗
PubMed1987

Elastosis in breast carcinoma: II. Association of protease inhibitors with immature elastic fibres.

The elastosis of 11 invasive ductal and infiltrative lobular carcinomas of the breast was specifically immunostained for the plasma protease inhibitors alpha-1 antitrypsin, alpha-1 antichymotrypsin, alpha-2 macroglobulin, inter alpha trypsin inhibitor and C1 esterase inhibitor. None of these components was detected in the elastic fibres of normal ducts or blood vessels in the breast. The elastosis in breast carcinomas was also stained by Concanavalin A and Triticum vulgaris lectins. Such lectin staining probably represents binding to the microfibrillar component of elastic fibres, which is increased in immature elastic fibres, thus suggesting that the elastotic fibres of breast carcinoma are recently synthesised. It is suggested that the presence of protease inhibitors may influence the metabolism of elastic fibres, facilitating elastic fibre proliferation by the inhibition of elastinolytic enzymes.

Adult↗
PubMed1987

Elastic fibres in normal and sun-damaged skin: an immunohistochemical study.

Sun-exposed and sun-protected skin obtained at post mortem from the nape of the neck in 14 subjects was immunostained using antisera to elastin, lysozyme, amyloid P component, and the plasma protease inhibitors alpha-I antitrypsin, alpha-I antichymotrypsin and alpha-2 macroglobulin. Both the normal elastic fibres in sun-protected skin, and elastosis in sun-exposed skin were positively immunostained for elastin, lysozyme and amyloid P component. Collagen fibres were unstained. No immunostaining of normal elastic fibres or elastosis in the skin was obtained with antisera to alpha-I antitrypsin, alpha-I antichymotrypsin or alpha-2 macroglobulin. It was concluded that the elastosis in sun-exposed skin does contain elastic fibres. The absence of immunostaining for plasma protease inhibitors probably indicates that the elastic material is mature, and not newly-formed.

Elastic Tissue↗