Nine herbicides and pesticides were tested for their mutagenicity using the Drosophila sex-linked recessive lethal mutation assay. These are Ambush, Treflan, Blazer, Roundup, 2,4-D Amine, Crossbow, Galecron, Pramitol, and Pondmaster. All of these are in wide use at present. Unlike adult feeding and injection assays, the larvae were allowed to grow in medium with the test chemical, thereby providing long and chronic exposure to the sensitive and dividing diploid cells, i.e., mitotically active spermatogonia and sensitive spermatocytes. All chemicals induced significant numbers of mutations in at least one of the cell types tested. Some of these compounds were found to be negative in earlier studies. An explanation for the difference in results is provided. It is probable that different germ cell stages and treatment regimens are suitable for different types of chemicals. larval treatment may still be valuable and can complement adult treatment in environmental mutagen testing.

2,4,5-Trichlorophenoxyacetic Acid↗

PubMed1995

Induction of delayed mutations by benzene and ethylene dibromide in Drosophila.

Two carcinogens, ethylene dibromide and benzene, were used to induce delayed (germinal mosaic) sex-linked recessive lethal mutations in spermatozoa and spermatids of adult Drosophila males. Significant numbers of delayed mutations (in F3) were scored in absence of conventional (in F2) mutations. A large proportion of nonlethal F2 cultures carried delayed mutations, so much so that, in some cultures, all F2 females were carriers of mutations. The mechanism through which single strand damage to treated X chromosomes can result in such delayed lethals is discussed. These observations indicate that the delayed mutation test should be used for testing the mutagenicity of environmental compounds, especially carcinogens, which tested negative in the conventional sex-linked recessive lethal mutation test. The data will support the relationship between mutagenesis and carcinogenesis and, also will further enhance the sensitivity of the Drosophila mutation assay.

Animals↗

PubMed1994

Health information for the developing world.

Doctors and other health professionals in developing countries are missing out on relevant information about health. A lot of the information they need is available in the developed countries, and those who have it are happy to share it with them. But transporting information, like food or medicines, from one part of the world to another is not an easy task nor is it the complete answer to the information drought. It is one thing to ferry books and journals from Europe to Africa and another to make relevant information available to the right person at the right time at an affordable cost.

Books↗

PubMed1993

Application of ESEM to environmental colloids.

Environmental colloids are toxic or radioactive particles suspended in ground or surface water. These hazardous particles can facilitate and accelerate the transport of toxicants and enhance the threat to humans by exposure to pathogenic substances. The chemical and physical properties of hazardous colloids have not been well characterized nor are there standard colloid remediation technologies to prevent their deleterious effects. Colloid characterization requires measurement of their size distribution, zeta potential, chemical composition, adsorption capacity, and morphology. The environmental scanning electron microscope (ESEM) by ElectroScan, Inc., analyzes particle sizes, composition, and morphology. It is also used in this study to identify the attachment of colloids onto packing or rock surfaces in our development of a colloid remediation process. The ESEM has confirmed the composition of groundwater colloids in our studies to be generally the same material as the surrounding rock. The morphology studies have generally shown that colloids are simply small pieces of the rock surface that has exfoliated into the surrounding water. However, in general, the source and chemical composition of groundwater colloids is site dependent. We have found that an ESEM works best as a valuable analysis tool within a suite of colloid characterization instruments.

Colloids↗

PubMed1987

Hereditary amyloid polyneuropathy in north west Ireland.

Seven cases of chronic sensorimotor polyneuropathy due to amyloidosis, from 7 different families, are described, in addition to the pathology in a sibling of 1 case. The age of onset ranged from 55 to 72 years. Cardiac involvement, intermittent diarrhoea and syncopal attacks were a frequent occurrence. Motor conduction velocity showed a moderate degree of slowing in 5 of 6 cases studied and marked slowing in 1. Amyloid deposits were seen in nerve biopsy material of all 8 subjects and in rectal mucosa from 1. Immunohistochemical identification revealed AF (transthyretin-derived)--amyloid in all 8 instances, confirming the presence of type 1 familial amyloid neuropathy. The genealogical data supported this analysis. Six of the 8 cases originated in a small area of the north-west coast of County Donegal in Ireland. The remaining cases also originated in the same county.

Aged↗

PubMed1983

No liquid holding recovery for chromosomal aberrations or sister-chromatid exchanges in irradiated G1 human lymphocytes.

We have tested G0 phase human peripheral lymphocytes for liquid holding recovery (LHR) mediated decreases in X-ray-induced chromosomal aberration yields and increases in sister-chromatid exchange (SCE) levels such as have been demonstrated for confluency-inhibited mouse cells in culture (Nagasawa and Little, 1981). No influence on either aberration yields or SCE levels was demonstrated. However, an effect at least superficially similar to the LHR effect was seen for rings and dicentrics, but not for deletions or SCE in lymphocytes in transition between G0 and G1 following PHA stimulation.

Chromosome Aberrations↗