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Biomedical subjects

D T Williams

Publications and source records attributed to D T Williams.

At least 19 recordsLinked to original sources
PubMed1992

Decrease in erythrocyte glycophorin sialic acid content is associated with increased erythrocyte aggregation in human diabetes.

1. Sialic acid moieties of erythrocyte membrane glycoproteins are the principal determinants of the negative charge on the cell surface. The resultant electrostatic repulsion between the cells reduces erythrocyte aggregation and hence the low shear rate viscosity and yield stress of blood. 2. Using g.c.-m.s., a decrease in sialic acid content has been observed in the major erythrocyte membrane glycoprotein, glycophorin A, obtained from nine diabetic patients compared with that from seven normal control subjects [median (range): 3.30 (0.01-11.90) versus 18.60 (3.20-32.60) micrograms/100 micrograms of protein, P less than 0.02]. 3. Erythrocyte aggregation, measured by viscometry as the ratio of suspension viscosity to supernatant viscosity (LS/S) in fibrinogen solution, was increased in ten diabetic patients compared with ten normal control subjects (mean +/- SEM, 37.6 +/- 1.3 versus 33.8 +/- 0.6, P less than 0.02). 4. In the patients in whom both viscometry and carbohydrate analysis were performed, the decrease in erythrocyte glycophorin sialylation and the increase in erythrocyte aggregation in fibrinogen solution were related statistically (LS/S correlated negatively with glycophorin sialic acid content, r = 0.73, P less than 0.05). 5. Decreased glycophorin sialylation provides an explanation at the molecular level for increased erythrocyte aggregation and it may be important in the pathogenesis of vascular disease in diabetes.

Adult↗
PubMed1990

Determination of organic contaminants in residential indoor air using an adsorption-thermal desorption technique.

This field study evaluated the ability of a multi-sorbent sampling tube/thermal desorption technique to identify and to provide quantitative data on volatile organic contaminants in indoor air. Air samples, from 12 Canadian homes, were collected on multilayer sorbent cartridges and analyzed using Adsorption/Thermal Desorption coupled with Gas Chromatography/Mass Spectrometry. The study included the identification and quantitation of 23 target compounds. Analysis of sorbent tubes fortified with these target compounds indicated that recoveries were greater than 70 percent and the precision was usually better than 15 percent. These organic compounds were found to be stable on the sorbent tubes for at least seven days. With some exceptions, the target compounds were usually detected at 1 to 10 micrograms/m3 in indoor air samples; other organics identified qualitatively were saturated hydrocarbons, unsaturated hydrocarbons, cyclic hydrocarbons, substituted aromatics, oxygenates, some halogenates and cyclic species such as camphenes/pinenes and carenes.

Adsorption↗
PubMed1987

Unilateral pigmented mobile vitreous cyst.

A patient presented with a pigmented mobile vitreous cyst in the right eye. The cyst was 6-7 mm in diameter, and was free-floating in the inferior half of the vitreous with no apparent attachments. No other ocular pathology was present in either eye. The patient became symptomatic only when the cyst obscured the visual axis. The literature was reviewed and will be discussed in this report.

Adult↗
PubMed1979

Mutagenicity of organic extracts from Canadian drinking water in the Salmonella/mammalian-microsome assay.

Organic extracts of chlorinated Ontario drinking water samples have been found to induce mutation and lethality in the Salmonella/mammalian-microsome histadine reversion assay. Collections of water were made at water treatment plants in five municipalities in June 1978. To determine the reproducibility of the positive mutagenic effects found, a second sampling at the same plants was performed in September 1978. Preparation of extracts involved passing 200 liter samples through XAD-2 resin columns which were eluted with a mixture of hexane and acetone, and the eluent was evaporated to dryness. For those extracts with sufficient organic matter, dose-related increases in mutagenicity were observed. Extracts of untreated water from a river and a well were weakly mutagenic.

Dose-Response Relationship, Drug↗
PubMed1979

The determination of polycyclic aromatic hydrocarbons at the ng/L level in Ottawa tap water.

Samples of Ottawa drinking water, collected in January and February 1978 were analysed by Gas Chromatography/Mass Spectrometry (GC/MS) for fifty polycyclic aromatic hydrocarbons (PAH) and five oxygenated polycyclic aromatic hydrocarbons (O-PAH), following extraction of the organic species using Amberlite XAD-2 macroreticular resin. In the January sample, thirty PAHs, ranging in concentration from 0.05 to 14 ng/L with a mean value of 3.8 ng/L and a total weight of 114 ng/L and four O-PAHs, ranging in concentration from 0.10 to 1.8 ng/L with a mean value of 0.91 ng/L and a total weight of 3.7 ng/L, were detected. In the February sample, thirty-six PAHs, ranging in concentration from 0.05 to 8.1 ng/L with a mean value of 1.4 ng/L and a total weight of 50.4 ng/L and five O-PAHs, ranging in concentration from 0.20 to 2.4 ng/L with a mean value of 1.0 ng/L and a total weight of 5.2 ng/L, were detected. Twenty-eight PAHs and four O-pahs were common to the two samples. The use of Amberlite XAD-2 macroreticular resin to extract PAHs from drinking water is shown to be effective, although the recovery of individual PAHs from artificially loaded XAD-2 resin varied from 57 to 100%.

Chromatography, Gas↗
PubMed1979

The impact of psychiatric intervention on patients with uncontrolled seizures.

There is much evidence that emotional stess can trigger both neurogenic and hysterical seizures in susceptible patients. We reviewed out experience with 37 patients whose seizures appeared to be precipitated at times by emotional stress and had not been controlled by anticonvulsant medication alone. Approximately 70 per cent of patients demonstrated substantial improvement in seizure control after psychiatric treatment and maintained this improvement during follow-up. The findings of this study suggest that patient characteristics associated with better prognosis include normal intelligence, partial (as opposed to generalized) neurogenic seizures, a diagnosis of hysterical seizures, a less severely abnormal EEG, and being hypnotizable. After psychiatric treatment, 32 per cent of patients had their anticonvulsant medication reduced and another 16 per cent had it discontinued.

Adolescent↗