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M Boyd

Publications and source records attributed to M Boyd.

At least 91 records · Page 5Linked to original sources
PubMed1978

The breath of life.

Explore the source record for details and available documents.

Child, Preschool↗
PubMed1977

Corneal endothelium bicarbonate transport and the effect of carbonic anhydrase inhibitors on endothelial permeability and fluxes and corneal thickness.

Unidirectional fluxes of bicarbonate across the corneal endothelium were determined. A net flux of bicarbonate from the stromal to aqueous-facing surface was demonstrated. Under conditions of carbonic anhydrase inhibition the net bicarbonate flux was reduced by 54 percent and the passive water permeability of the endothelium was increased. Experiments with the specular microscope demonstrated an increased rate of corneal swelling under conditions of carbonic anhydrase inhibition. Attempts to identify H+ as the cation moving with the bicarbonate ion to maintain electroneutrality were not successful because of the impossibility of sustaining a differential H+ concentration difference across the endothelium.

Animals↗
PubMed1976

An influenza simulation model for immunization studies.

A stochastic simulation epidemic model based on discrete time intervals and appropriate for any infectious agent spread by person-to-person contacts is presented. The population is highly structured, allowing for five age groups and for subgrouping mixing in families, neighborhoods, schools, and preschool playgroups as well as total community mixing. With proper choice of relative susceptibility by age, length of latency and infectivity periods, pathogenicity and withdrawal patterns, and the relative infectiousness of silent infections, the model becomes highly agent-specific. The model includes flexible immunization routines and variable vaccine response patterns. The model is applied to the 1957 Asian and 1968 Hong Kong pandemic strains of influenza A. The results of several schedules of immunization of school children are presented and compared for the two strains.

Adolescent↗
PubMed1976

Immigration policies and trends: a comparison of Canada and the United States.

This paper discusses recent migration to North America with reference to the 1962 and 1967 Canadian immigration regulations and the 1965 United States Immigration and Nationality Act. Despite the similar emphasis on manpower and kinship criteria as the basis for the admission of immigrants, differences between Canada and the United States exist with respect to the importance of immigration for the respective economies, the organization of immigration, the formal regulations, and the size and composition of migrant streams. After an examination of the volume, origin, and occupational composition of immigration to Canada and the United States, flows between the two countries are studied. The paper concludes with a scrutiny of changes in immigration regulations which are pending in both countries.

Africa↗
PubMedDate not supplied

A gene therapy/targeted radiotherapy strategy for radiation cell kill by.

BACKGROUND: Although [131I]meta-iodobenzylguanidine (MIBG) is currently one of the best agents available for targeted radiotherapy, its use is confined to a few neural crest derived tumours which accumulate the radiopharmaceutical via the noradrenaline transporter (NAT). To determine whether this drug could be used for the treatment of non-NAT expressing tumours following genetic manipulation, we previously showed that plasmid mediated transfection of NAT into a non-NAT expressing glioblastoma cell line, UVW, endowed the host cells with the capacity to actively accumulate [131I]MIBG. We now present data defining the conditions required for complete sterilisation of NAT transfected cells cultured as multicellular spheroids and treated with [131I]MIBG. METHODS: NAT transfected UVW cells, grown as monolayers and spheroids, were treated with various doses of [131I]MIBG and assessed for cell kill by clonogenic survival and measurement of spheroid volume over time (growth delay). Spheroids were left intact for different time periods to assess the effect of radiation crossfire on cell death. RESULTS AND CONCLUSIONS: Total clonogen sterilisation was observed when the cells were grown as three-dimensional spheroids and treated with 7 MBq/ml [131I]MIBG. The added benefit of radiation crossfire was demonstrated by the improvement in cell kill achieved by prolongation of the maintenance of [131I]MIBG treated spheroids in their three-dimensional form, before disaggregation and clonogenic assay. When left intact for 48 h after treatment, spheroid cure was achieved by exposure to 6 MBq/ml [131I]MIBG. These results demonstrate that the efficiency of cell kill by [131I]MIBG targeted therapy is strongly dependent on beta-particle crossfire irradiation. This gene therapy/targeted radiotherapy strategy has potential for [131I]MIBG mediated cell kill in tumours other than those derived from the neural crest.

3-Iodobenzylguanidine↗
PubMedDate not supplied

Transfectant mosaic spheroids: a new model for evaluation of tumour cell killing in targeted radiotherapy and experimental gene therapy.

BACKGROUND: We describe an in vitro tumour model for targeted radiotherapy and gene therapy that incorporates cell population heterogeneity. MATERIALS AND METHODS: Transfectant mosaic spheroids (TMS) and transfected mosaic monolayers (TMM) are composed of two cell populations derived from a single cell line. The cells of one population were transfected with the noradrenaline transporter gene (NAT), allowing active uptake of a radiolabelled targeting agent meta-[131I]iodobenzylguanidine ([131I]MIBG); the other population of cells was derived from the same parent line and transfected with a marker gene - green fluorescent protein (GFP). After treatment with [131I]MIBG, cell kill was determined in TMM by clonogenic assay and in TMS by clonogenic assay and spheroid growth delay. RESULTS: We have used the TMS model to assess the 'radiological bystander effect' (radiation cross-fire) conferred by the beta-emitting radiopharmaceutical [131I] MIBG whose cellular uptake is facilitated by the transfected gene encoding NAT. We show that cell killing by [131I]MIBG in both TMS and TMM cultures increased in direct proportion to the fraction of NAT-transfected cells and that the degree of cell killing against fraction transfected was greater in TMS, suggestive of a greater bystander effect in the three-dimensional culture system. CONCLUSIONS: TMS provide a useful model for assessment of the effectiveness of targeted radiotherapy in combination with gene therapy when less than 100% of the target cell population is expressing the NAT transgene. Further, this novel model offers the unique opportunity to investigate radiation-induced bystander effects and their contribution to cell cytotoxicity in radiotherapy and other gene therapy applications.

3-Iodobenzylguanidine↗