Kinetic studies of "sex ratio" spirochetes in Drosophila melanogaster Meigen females.
Explore the source record for details and available documents.
Bacteria↗
Biomedical subjects
D L Williamson
Publications and source records attributed to D L Williamson.
Transmission by injection of hybrid sterility to nonhybrid males in Drosophila paulistorum: preliminary report.
Explore the source record for details and available documents.
Animals↗
Studies on the pathogenicity of spiroplasmas for Drosophila pseudoobscura.
Representatives of several currently available spiroplasma serovars were used in feeding and injection experiments involving Drosophila pseudoobscura adult flies in order to evaluate the host-range of the spiroplasmas and to determine their pathogenicity for flies. Many of the isolates injected into flies either do not survive or grow poorly, and have no negative effects on longevity or fecundity. Two spiroplasma strains, honey-bee (serovar I-2) and cornstunt (serovar I-3), can grow to high titres in injected flies but are not pathogenic. In addition to the special pathology of male lethality caused by the sex-ratio organisms (spiroplasmas) which occur naturally in several neotropical species of Drosophila, two spiroplasma serovars resulted in the death of injected flies. Spiroplasmas isolated from syrphid flies (serovar VIII) and from Cotinus beetles (serovar IX) induced the appearance of symptoms of pathology that eventually culminated in death. All such flies which were examined for the presence of spiroplasmas in their haemolymph showed them to be present in very high concentrations. The numbers of progeny which these flies produced were greatly reduced, but did consist of equal numbers of flies of both sexes. Spiroplasmas from their infected female parents were not vertically (transovarially) transmitted. The results of the feeding experiments were all negative: none of the spiroplasmas persisted in the gut or appeared in the haemolymph. None of the flies which had been fed the spiroplasma suspension displayed any pathology.
Animals↗
Enhancing low-income parents' capacities to promote their children's health: education is not enough.
In 1996 the Capital Heath Region in Edmonton, Alberta integrated a primary health care component into Head Start programs. One aspect of the primary health care component (PHC-HS) was a series of education sessions aimed at strengthening parents' capacities to enhance their children's health. To make the education sessions relevant, 10 focus groups with 65 parents of children who attended Head Start were conducted prior to the sessions. Findings indicated that participants' ability to enhance their children's health and manage their children's illnesses was limited as much by low incomes, inadequate health care coverage, and lack of transportation as it was by a lack of knowledge. Results provide evidence that health education sessions alone are not adequate to significantly enhance low-income parents' capacities to promote their children's health. Efforts to strengthen the abilities of low-income individuals and families to promote their health will be most effective if health education is accompanied by policy advocacy and social action strategies that challenge the socioeconomic and political conditions that negatively affect health. Public health nursing's commitment to social justice, as well as findings about the limitations that low incomes, inadequate health care benefits, and lack of transportation placed on participants' ability to enhance their children's health, underscore the need for public health nurses (PHNs) to address structural conditions contributing to health inequities. As such, an overview of literature that details strategies and theoretical models for challenging socioeconomic and political conditions which restrict the ability of low-income individuals and families to enhance their health is provided.
Adult↗
Characterization of spiroplasmas by serology.
Five major serologic groups of spiroplasmas have been distinguished on the basis of serology (as determined in a test of deformation and metabolism inhibition), guanine-plus-cytosine content of DNA, and DNA-DNA hybridization. group I includes strains of Spiroplasma citri that form a classical subgroup (serovar) complex of four serologically homogeneous serovars that cross-react with each other at varying levels. The four other serogroups do not cross-react with each other or with members of the group I S. citri complex. Group II consists of the sex ratio spiroplasma from Drosophila species. Group III contains spiroplasmas isolated from flowers of magnolia and tulip trees. Group IV consists of strains of spiroplasmas recovered from insects and flowers. The tick-derived spiroplasmas SMCA and TP-2 compose group V.
Cytosine↗
The use of population health and health promotion research by health regions in Canada.
This study examined the use of population health and health promotion (PH&HP) research by health regions in Canada. An 11-item survey was faxed to 137 (of 140) health regions. Eighty-three completed questionnaires were returned (60.8%). Results indicate that while research, in general, plays more than a moderate role in the majority of participating health regions, PH&HP research is not used frequently. The most frequent uses of PH&HP research include the development of health goals and objectives, the development of programs and services, and resource allocation. Health regions most frequently obtain PH&HP research from their own staff and from government departments. University-based researchers are not a commonly used source. This study provides a descriptive overview of health regions' engagement in evidence-based decision making related to PH&HP issues, and points to a number of strategies that both health regions and researchers can employ to enhance the use of PH&HP research by health regions.
Canada↗
The role of the health sector in addressing poverty.
PURPOSE: To explore Canadian health sector initiatives addressing poverty. METHODS: Information about 224 health sector initiatives addressing poverty was collected from Health Canada, provincial/territorial health ministries, and health regions. RESULTS: Health Canada, 12 provincial/territorial health ministries, and at least one third of health regions have been undertaking poverty-related initiatives. Almost two thirds (64.7%) of initiatives focused on the consequences of poverty. Much less frequent were initiatives that aim to: raise awareness about poverty; prevent people from becoming poor; enhance skills and education of people in poverty; and alter social and economic conditions contributing to poverty. DISCUSSION AND CONCLUSIONS: While strategies that focus on the consequences of poverty likely enhance the health of Canadians in poverty, these strategies do little to reduce poverty rates. Efforts to improve the health of both individual Canadians in poverty and society as a whole will be limited until the health sector uses more strategies that challenge fundamental structural conditions contributing to poverty.
Canada↗
Spiroplasma taxonomy and identification of the sex ratio organisms: can they be cultivated?
The spiroplasmas that occur naturally in several species of Drosophila were the first spiroplasmas ever observed, even though their discoverers, D.F. Poulson and B. Sakaguchi, in 1961 described them as being "treponema-like spirochetes." These Drosophila spiroplasmas are transovarially, or maternally, transmitted by infected females whose progenies are composed entirely of females. A more recently discovered Drosophila spiroplasma found in flies originating in Ito, Japan, is also maternally inherited but does not result in the elimination of males from the progeny of infected females. In spite of their early discovery, their high numerical density in the hemolymph of infected females (10(6)-10(7)/microliters), and numerous attempts at in vitro cultivation, they remain prime examples of non-cultivable spiroplasmas. It is the purpose of this paper to recount some of the approaches used in attempts at their cultivation.
Animals↗
Characterization and taxonomic status of tick spiroplasmas: a review.
Three serologically distinct groups of spiroplasmas have been recovered from ticks. Spiroplasma mirum strains (from rabbit ticks, Haemaphysalis leporispalustris) and Y32 group (VI) spiroplasmas (from Ixodes pacificus) are the only spiroplasmas to have a clear association with these arthropods. Group (VI) spiroplasmas are distinguished by an unusual nonhelical morphology and their capacity to hemadsorb guinea pig erythrocytes. S. mirum strains are unique in their ability to induce cataracts or lethal brain infections in a number of young vertebrates and in their virulence for the chick embryo. The 277F spiroplasma, while initially recovered from a pool of rabbit ticks (H. leporispalustris), is related by certain serological and genetic properties to spiroplasmas in the S. citri complex (serogroup I). These relationships suggest that the 277F spiroplasma may not be a natural inhabitant of the rabbit tick.
Animals↗
Poverty and medical treatment: when public policy compromises accessibility.
PURPOSE: To explore poor Edmontonians' access to medical treatment services. METHODS: Data were collected during interviews with 130 poor Edmontonians. RESULTS: 38% of study participants had failed to obtain physician services when they were sick or bothered by a health problem, and 40% who had been prescribed a medication had not filled the prescription. Participants experienced three main barriers to access: lack of money, lack of comprehensive health care coverage, and lack of affordable transportation. Findings suggest that a variety of health care and social assistance policies limit access to treatment services for people living in poor families. CONCLUSION: Despite the principles of the Canada Health Act, access to medical treatment is not based solely on need, but is tied, in part, to income. There is a need for health care, social, and economic policies that aim to reduce the barriers that limit access to physician services and prescription medications by people living in poverty.
Adolescent↗