Biomedical subjects
Publications and source records attributed to G A Luke.
The "one gene = one protein" model for understanding the genome is well-known. But, as with most biological "rules", it has its exceptions. The viral family that brings polio, the common cold and foot-and-mouth disease translates its entire genome into one long "polyprotein". The study of this translation strategy is bringing to light new targets for fighting disease and new techniques for the biotech industry.
The aetiology of dental caries is in part related to the retention time of dietary carbohydrates in the oral cavity and their subsequent metabolism by the oral bacteria. Salivary clearance of fermentable carbohydrates from three different foodstuffs was examined in 5 subjects and analyses performed by high-performance anion-exchange chromatography with pulsed amperometric detection. The clearance of glucose, fructose, sucrose, maltose and sorbitol rinses was studied as well as that of chocolate bars, white bread and bananas. Of the sugar rinses studied, sucrose was removed from saliva most rapidly whilst appreciable levels of sorbitol remained even after 1 h. Clearance of residual carbohydrates from bananas and chocolate bars seemed marginally faster than in the case of bread, but sucrose levels still tended to fall more quickly than other carbohydrates studied. Surprisingly, carbohydrate residues from the three foods studied were still present in the mouth even 1 h after ingestion, which is longer than has hitherto been reported.
Preconceptional paternal irradiation has been implicated as a causal factor in childhood cancer and it has been suggested that this exposure to radiation may play a role in the occurrence of childhood leukaemia clusters in the vicinity of nuclear installations. Using a transgenic mouse system employing a lambda shuttle vector allowing mutations (in the lacI gene) to be analysed in vitro, we have investigated the possibility that preconceptional paternal irradiation can lead to such transgenerational transmission of genomic instability. We have examined the mutation frequencies in vector recovered from the bone-marrow cells of the F1 offspring of male parents exposed to doses of gamma-rays of 0.1-4 Gy. Our results show that as parental dose increases there is a trend towards higher mutation frequency in vector recovered from the DNA of bone-marrow of F1 progeny. At 4 Gy the frequency of mutations was increased by a factor of approximately two (control mutation frequency, 2.39 x 10(-5); mutation frequency in offspring of 4 Gy male group, 4.26 x 10(-5); P < 0.001). We were unable to confirm reports of spermatogenesis stage sensitivity. The 2-fold increase in mutation frequency was evident in offspring derived from stored spermatozoa (irradiated transgenic males mated with unirradiated non-transgenic females 1-7 days after irradiation). Our data indicates that there exists a route for transgenerational transmission of factor(s) leading to genomic instability in F1 progeny, resulting from preconceptional paternal irradiation.
The aim of this project was to develop an analytical procedure with the required level of sensitivity for the determination of glucose concentrations in small volumes of unstimulated fasting whole saliva. The technique involves high-performance ion-exchange chromatography at high pH and pulsed amperometric detection. It has a high level of reproducibility, a sensitivity as low as 0.1 mumol/l and requires only 50 microliters samples (sensitivity = 0.002 pmol). Inhibition of glucose metabolism, by procedures such as collection into 0.1% (w/v) sodium fluoride, was shown to be essential if accurate results are to be obtained. Collection on to ice followed by storage at -20 degrees C was shown to be unsuitable and resulted in glucose loss by degradation. There were inter- and intraindividual variations in the glucose concentration in unstimulated mixed saliva (range; 0.02-0.4 mmol/l). The procedure can be used for the analysis of other salivary carbohydrates and for monitoring the clearance of dietary carbohydrates from the mouth.