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At least 1,207 records · Page 67Linked to original sources
PubMed1981

Exposure of man to environmental arsenic - an exposure commitment assessment.

The Monitoring and Assessment Research Centre (MARC) has been developing and applying the exposure commitment method to the assessment of pollutant transport in the regional and global environment. Exposure commitments give a basis for comparing contributions to exposure from various pathways and for estimating equilibrium concentrations resulting from continuing releases. As an illustration of the method, environmental aspects of arsenic are summarised and relationships are formulated between environmental sources and concentrations of arsenic in the body. Arsenic is present in the environment primarily in inorganic form; however, relatively higher concentrations of arsenic in organic forms occur in fish. Ingestion intake by man is variable, dependent on seafood consumption and also on geography, determining for example the levels which may be present in drinking water. Based on measured absorption and retention of arsenic in man, it is estimated that an ingestion intake rate of arsenic in terrestrial foods of 1 mg y-1 contributes a concentration of arsenic in the body of 0.28 microgram kg-1. The relationship is 0.14 microgram kg-1 per mg y-1 intake of organic arsenic in seafood. The body burden of arsenic is estimated to be about 1 mg from reported tissue measurements and from representative intake estimates. Harmful effects from arsenic in the body could be expected at levels perhaps 5 to 80 times the current background levels. Uncertainties are recognized. Improved estimates of the transfer fractions can be made as additional data are acquired.

Air Pollutants↗
PubMed1984

Air pollutants, bronchial hyperreactivity, and exercise.

The interaction of air pollutants and their effect on bronchial hyperreactivity show that sulfur dioxide and ozone both increase bronchial hyperreactivity. Sulfur dioxide concentrates as low as 0.5 ppm and ozone concentrations as low as 0.2 ppm have demonstrated this effect. Exercise with either sulfur dioxide or ozone exposure can significantly increase bronchial hyperreactivity in susceptible individuals. Other factors including ambient air temperature, time of day, wind velocity and direction, geography, climate, tobacco smoke exposure, and other indoor air pollutants may enhance the impact of air pollutants, causing bronchial hyperreactivity.

Adaptation, Physiological↗
PubMed1991

Cockroach-allergen study: allergen patterns of three common cockroach species probed by allergic sera collected in two cities.

Antigens/allergens of three common cockroach extracts, crude whole body extract of the American cockroach (CRa-A), crude whole body extract of the German cockroach (CRa-G), and crude whole body extract of the Oriental cockroach (CRa-O), were studied with crossed immunoelectrophoresis, crossed radioimmunoelectrophoresis, and Western blot analysis. Sera of cockroach-allergic patients with asthma, 10 from Chicago, Ill. (C group) and six patients from Lexington, Ky. (L group), were used; results were then compared with sera of control subjects with asthma. Qualitative differences in protein bands were noted among CRa-A, CRa-G, and CRa-O by crossed immunoelectrophoresis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Allergen bands on Western blot were analyzed for distribution by molecular weight (MW) with relative intensity scores. Results were compared by species and by geography. Two to 12 allergenic bands of variable MW (14 kd to greater than 116 kd) were identified by 13 of 16 individual sera from cockroach-allergic patients from all three extracts. CRa-A demonstrated 55 bands with an intensity score of 125; CRa-G, 58 bands with an intensity score of 100; and CRa-O, 51 bands with an intensity score of 108. Allergenic bands of CRa-A were identified by six sera of the C group and one sera of the L group, whereas bands of both CRa-G and CRa-O were noted by nine sera of the C group and four sera of the L group. All three species had an allergen band in MW range of 40 to 45 kd that reacted to most sera from cockroach-allergic patients with asthma.

Adolescent↗
PubMed1994

Negative selection of lymphocytes.

Almost by definition, negative selection of T and B lymphocytes cannot be absolute. Given that both sets of receptors are derived by stochastic processes, recognition of epitopes by lymphocyte receptors will not be an all or none affair but a relative one. Too effective a mechanism of negative selection would have resulted in deletion of the whole repertoire, as all specificities would have cross-reacted with some self-epitope at least to some degree. This review has documented some of the influences impacting on emerging T and B cell repertoires that result in a removal of the most dangerous self-reactive cells and the progressive quantitative and qualitative increase, through positive clonal selection, of other cells specific for the actual foreign antigens encountered by each individual. T and B lymphocytes pass through a stage where their natural reaction to antigen is one of negative selection and on to a later stage where the cell is more likely to become activated. Geography plays a role in this; the primary lymphoid organs are designed largely to exclude foreign antigens and to present self-antigens, whereas the secondary lymphoid organs are designed to filter out and concentrate foreign material and to promote costimulatory intercellular immune interactions. Ontogeny of individual cells also plays its role, probably through the progressive assembly of the full receptor signaling machinery, incomplete arrays promoting a negative rather than a positive signal. However, the differing susceptibilities of immature and mature cells to silencing by deletion or anergy are relative rather than absolute. Negative signaling may involve immediate or somewhat delayed death of the anti-self-cell, and in some cases the bad cell may have the chance of editing its receptor to create one lacking anti-self-reactivity. Alternatively, the cell may receive a nonlethal down-regulatory signal and may be induced into a state of anergy. Such anergic cells may have a reduced life span, showing that anergy and deletion may shade into each other. Upon the removal of antigen (an unlikely event for cells anergic to an authentic self-antigen), the state of anergy is reversible. The strength of the receptor cross-linking signal may chiefly determine whether deletion (strong cross-linking) or anergy (weaker cross-linking) supervenes. Some lymphocytes with self-reactivity ignore the self-antigen in question because of low affinity, poor accessibility, lack of suitable presentation, or absence of appropriate help.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Symbolic keyboard for computer aided instruction of deaf children.

We describe a computer-based method for the special education of deaf children in their stage of expanding an initial vocabulary; the method uses a symbolic keyboard to facilitate real-time communication between the deaf child and the machine. The lack of auditory feedback is partially compensated by using visual and proprioceptive sensorial modalities as alternative representations of words and concepts. To illustrate the use of the computer with display and symbolic keyboard we comment on a program for the teaching of spatial relationships. The same method is used in teaching the structure of sentences and other conventional educational material such as Geography and Physics.

Biomedical Engineering↗
PubMed1990

Health care technology in Australia and New Zealand: contrasts and cooperation.

Australia and New Zealand are neighbouring countries with similarities due to their settlement by Europeans, but with major differences in their economies, populations, geography and political systems. These differences have led to contrasting approaches to the introduction and control of health care technologies. New Zealand has historically had greater success in limiting the use of health technologies which have often been adopted more widely and rapidly in Australia. Recent initiatives in health technology assessment have involved participation by both countries, giving the potential for a joint approach to policy formulation on use of some medical devices and procedures.

Australia↗
PubMed1995

Satisfaction and continuity of care: staff views of care in a midwife-managed delivery unit.

OBJECTIVE: to examine whether there are differences in the midwife's role in, and satisfaction with, intrapartum care and delivery of women at low obstetric risk in a midwife-managed delivery unit compared to a consultant-led labour ward. DESIGN: a pragmatic randomised controlled trial. Subjects were randomised in a 2:1 ratio between the midwives' unit and the labour ward. SETTING: Aberdeen Maternity Hospital, Grampian, UK. SUBJECTS: midwives within the delivery suite who cared for the 2844 women at low obstetric risk receiving care in a pragmatic randomised controlled trial of the two delivery areas. PRIMARY OUTCOME MEASURES: continuity of carer and midwife satisfaction. FINDINGS: midwives looking after women in the midwives' unit group were significantly more likely to be of a higher grade, more qualified and have a longer length of experience than those in the labour ward group. There was greater continuity of carer both during labour and after delivery in the midwives' unit group. Despite a small but statistically significant difference in overall satisfaction between the groups, area of 'booking' or area of delivery were not important in predicting midwife satisfaction. Autonomy and continuity of carer were the best predictors of midwife satisfaction. CONCLUSIONS: midwife-managed intrapartum care increases continuity of carer and, therefore, midwife satisfaction. Extending this outside the delivery suite requires a system of care that is acceptable to midwives as well as women. Such systems will depend to a large extent on geography, consumer demand and availability of resources. However, midwife satisfaction should also be considered. In order to do this further research is required to fully evaluate the effect these systems have on the midwives working in them.

Attitude of Health Personnel↗
PubMed1986

The use of epidemiology, scientific data, and regulatory authority to determine risk factors in cancers of some organs of the digestive system. 5. Stomach cancer.

In 1930, stomach cancer was the leading cause of death due to cancer among men in the United States. Among women it was the third leading cause of cancer deaths. Although it is well known that death rates for stomach cancer have diminished dramatically over the past 50 years, stomach cancer still has the third poorest 5-year relative survival rate of the different cancers, after pancreatic and lung cancer. Most evidence indicates that environmental factors play an important role in the development of stomach cancer. The remarkable decrease in stomach cancer mortality over the past 50 years and the results of a variety of migrant studies support this review. Several published case-control studies have shown positive associations with preserved meat and salted and pickled food in general. However, there are negative associations with vegetables, fruits and milk; vitamin C is implicated. Milk has both positive and negative associations. This points to the possibility of a carcinogen produced by traditional preservation methods such as salting and suggests that fresh vegetables and fruits and high intakes of vitamin C may reduce the risk. What specific role/s the diet plays in the incidence of stomach cancer remains to be seen. There is a need to elaborate the relationship of such factors as age, sex, migration, geography, environmental factors, and diet to the carcinogenic process that produces cancer of the stomach.

Age Factors↗
PubMed1984

Ill-health and health-care in Khartoum/Omdurman.

Medical geographies of Third World cities are particularly affected by lack of data of sufficient detail and spatial resolution to allow proper analysis of intra-urban patterns of variation. Rapid rates of population growth fuelled both by natural increase and migration compound the problem of demographic accounting. Khartoum/Omdurman, the major urban complex in the Sudan is no exception to this situation and although some available statistical information from official sources is used to portray some of the characteristics of urban ill health, greater reliance is placed upon data collected during a social survey of seven contrasted residential areas. Whilst the extent of under-reporting of disease and the typical patterns of ill-health become apparent, it is also clear that there are very large differences among the different types of residential area. The gap between rich and poor, manifest in many criteria of social well-being, is also no less acute in terms of vulnerability to disease. It is also evident that although quality of services is generally problematic, something resembling an 'inverse-care' situation seems to exist which further exacerbates the disadvantage of poor urban dwellers.

Delivery of Health Care↗
PubMed1985

Space and time in British general practice.

From the novel geography of the health centre to the meticulous concerns of appointment systems and patient records, British general practice, as this paper documents, has reordered its traditional activities over the last 30 years. These changes however suggest a more profound reorganisation of the spatial and temporal features of practice activity and a commensurate reassessment of the nature of illness.

Community Health Services↗
PubMed1985

Water resources development and schistosomiasis ecology in the Awash Valley, Ethiopia.

This paper examines the impact of water resources development, particularly river regulation and irrigated agriculture, on the occurrence of schistosomiasis and its intermediate host snails in the Awash Valley. An ecologic-geographic approach based on: a combination of comparative schistosomiasis prevalence and human ecological studies of indigenous seminomadic pastoralists and migrant laborers from the Ethiopian highlands; analysis of snail intermediate host ecology-geography; and longitudinal studies of water resources development, is used to evaluate the endemicity status and changing spatial distribution of schistosomiasis mansoni and schistosomiasis haematobium. This study confirms the suitability of epidemiologic-ecologic methods for analyzing relationships between causal processes and the spatiality of schistosomiasis. In this context local schistosomiasis control programs are reviewed and recommendations made for their improvements.

Agriculture↗
PubMed1986

Cultural components of behavioural epidemiology: implications for primary health care.

In this article we discuss the association of culturally linked behaviour and epidemiology: that patterns of disease are significantly related to cultural sets of normative beliefs and behaviour. The literature on this is vast and includes much of what is written under the headings of Medical Anthropology as well as, for example, Cross-cultural Psychiatry and Medical Geography. A comprehensive review is obviously impossible, but as this is presented primarily as a background paper, basic issues are raised, and related to examples from the literature, to stimulate discussion. The article is divided into four subsections which give an indication of our focus: culture, disease and illness causation; utilization and provision of health resources; health, illness and normative socio-political and economic behaviour and primary health care, community participation and culture--implications for the future.

Behavioral Sciences↗
PubMed1987

The impact and integration of behavioural sciences in the education of health care professionals.

Health, defined as physical, mental and social well-being, should be adequately conceptualized in organic as well as non-organic terms, thus implying a criticism of some training programmes which ought to recognize the dire need to integrate the socio-behavioural sciences--geography, social anthropology, sociology, psychology, political science and economics--in the education of health care professionals. The two components of this education, medicine and health care and the socio-behavioural sciences, should prepare the professional adequately to practice the science of medicine and the art of the profession in varying socio-cultural contexts of co-existing health care systems. This paper argues that it is only those institutions which integrate the socio-behavioural sciences in their programme of health care education that are on the path of progress by keeping scientific pace with our understanding of the structural realities of contemporary societies.

Behavioral Sciences↗
PubMed1990

Activism for medical geographers: American, British and Canadian viewpoints.

This paper describes some of our personal efforts to launch research projects that address public health issues of interest to geographers in the United States, Canada and Britain. In pressing these agendas we have found through our experiences that there are personal and disciplinary costs associated with activism. We describe the loss of identity with geography; the frustration of trying to persuade bench scientists, corporate representatives, and government officials of the importance of our work; the loss of research time and contact with both our academic colleagues and students.

Adolescent↗
PubMed1991

Another day in paradise? Life on the margins in urban New Zealand.

This paper examines the relationships between housing and health with respect to a sample of New Zealand public housing applicants. In the first part of the paper, the notion of incipient homelessness is reviewed, the production of this population in advanced capitalist societies is considered and the social geography of the inadequately housed in New Zealand is surveyed. The second part of the paper presents some of the data collected in a survey of the inadequately housed in Auckland and Christchurch (n = 213 households). The results suggest that housing is an important determinant of the health and well-being of this population, but that rehousing the poor should be seen as only one step in addressing inequalities in contemporary urban New Zealand.

Ethnicity↗
PubMed1991

Geographical variations of motor-vehicle injuries in Quebec, 1983-1988.

Data furnished by the Régie de l'Assurance Automobile du Québec (RAAQ) were used to describe the geography of motor vehicle accidents in the province of Quebec for the period 1983-1988. These were also used to evaluate the risk factors associated with zones of high risk with regards to accidents for the 97 Municipalités Régionales de Comté (MRC). The results demonstrate that non-severe accidents are more frequent in the urban context. On the other hand, severe accidents are more frequent in the rural context. The Standard Morbidity Ratio (SMR) highlights those MRC's with the risk of severe or non-severe accidents, where risks are twice that of Quebec as a whole. The demographic characteristics (age, sex) of the driver and passengers and the place of the accident (region, density) were used in the model LOGIT to evaluate risk factors associated with high risk zones. Results of the model for those severely injured are different from those for non-severely injured people. This holds true for the location of accidents as well as for demographic characteristics. In both models, women and people over 65 years of age are low-risk groups for accidents. The authors indicate certain action to be undertaken in Quebec by the Government to improve this situation.

Accidents, Traffic↗
PubMed1992

Challenges to understanding spatial patterns of disease: philosophical alternatives to logical positivism.

Most studies of disease distribution, in medical geography and other related disciplines, have been empirical in nature and rooted in the assumptions of logical positivism. However, some of the more newly articulated philosophies of the social sciences, and of social theory, have much to add in the understanding of the processes and mechanisms underlying disease distribution. This paper represents a plea for creative synthesis between logical positivism and realism or structuration, and uses specific examples to suggest how disease distribution, as a surface phenomenon, can be explained using deeper analysis.

Cross-Cultural Comparison↗
PubMed1993

[Geographic inequalities in HIV infection and AIDS in sub-saharan Africa].

The geography of HIV infection in Africa (which is the continent with the highest incidence rates) has varied features at each scale. The transmission is oriented preferentially according to axes and poles where the virus--because of local environmental factors--found favorable conditions to dissemination and spread. The dynamic of the epidemic results from factors related to sociologic, cultural, religious behaviour and to geographical, political and economic situations. The local combination of all the causal factors explains the complexity and diversity of the geographic characteristics of the African epidemic. The knowledge of the complexity and diversity of the geographic characteristics of the African epidemic. The knowledge of the causal factors calls upon various disciplines. Spatial networks, population movements and their consequences are analyzed. Geographical data together with sero-epidemiologic information initiate hypothesises related to the spatial dynamic of the epidemic and to the processes of regionalization.

Acquired Immunodeficiency Syndrome↗