Lipid lowering drugs in diabetes: lipid lowering has ophthalmic benefits.
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Diabetes Mellitus, Type 2↗
Biomedical subjects
Nigel Davies
Publications and source records attributed to Nigel Davies.
Intravitreal triamcinolone in diabetic macular edema.
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Diabetic Retinopathy↗
Comparison of logMAR ETDRS chart and a new computerised staircased procedure for assessment of the visual acuity of children.
The validity and repeatability of visual acuity measures are particularly important in the detection and monitoring of childhood visual anomalies such as amblyopia. The repeatability and sensitivity of a new computerised visual acuity test, 'Staircased Procedure' is compared with the now gold standard visual acuity test, the early treatment of diabetic retinopathy study (ETDRS). Twenty-seven visually normal children (mean age: 6.7 +/- 1.1 years) and 27 children with amblyopia (mean age: 6.1 +/- 0.7 years) were tested with the ETDRS and Staircased Procedure. A retest was administered 4-5 weeks later and 30 min later for the visually normal and the amblyopic children, respectively. The staircased procedure produced significantly better visual acuity than the ETDRS for visually normal and amblyopic children. Repeatability was similar for both tests (ETDRS: 0.11 log units; staircased procedure: 0.13 log units). In conclusion, the Staircased Procedure was an acceptable test with high repeatability and validity.
Amblyopia↗
Temporal visual filtering in diabetes mellitus.
The background modulation method was used to investigate the temporal response of the magnocellular pathway in diabetic patients and controls. The luminance threshold for detecting a moving, 2 degrees, achromatic target was measured as a function of background flicker frequency from 5 to 45 Hz. A model of photoreceptor kinetics integrated with difference of Gaussian receptive fields [Vis. Neurosci. 13 (1996) 173] was used to analyse the data. Diabetic patients with significant maculopathy showed raised thresholds at 8.75, 12.5, 15 and 17.5 Hz. Estimates of photoreceptor summation time were the same in both groups, but receptive field centre-to-surround delay showed an increasing trend in the diabetic patients.
Adult↗
A prolonged immune response to antigen delivered in poly (epsilon-caprolactone) microparticles.
A single dose vaccine formulation which induces both humoral and cell-mediated immune responses over a prolonged period would provide a potent weapon against infectious disease. We have used a water-in-oil-in-oil, solvent evaporation method for generating poly epsilon-caprolactone microparticles and tested their ability to induce an immune response against the model antigen ovalbumin. We hypothesized that the initial release of antigen from the surface of the poly epsilon-caprolactone microparticles would act as the priming dose and that the delayed release over the following months, due to diffusion from or break-down of the microparticles, would act as a boost to the immune response. Ovalbumin encapsulated in the poly epsilon-caprolactone microparticles was able to induce both antibody and cell-mediated immune responses. However our results suggest that the spontaneous release had little effect on the immune response. Despite this the response was maintained for at least 8 months following a single immunization. Both humoral and cell-mediated immune responses were induced in mice. This simple method of vaccine formulation offers a cost-efficient way to deliver antigen in a single dose to the immune system.
Animals↗
Repeatability of ocular wavefront measurement.
PURPOSE: To assess the repeatability of measurements of ocular aberrations using wavefront sensing in a small group of observers and to assess the potential effect of measurement error on custom corneal correction due to this variability. METHOD: A Shack-Hartmann wavefront sensor was used to measure the ocular wavefront in nine eyes. Head position was stabilized using a dental bite bar, and the pupil was centred using a cathode ray tube monitor and circular grating. Twenty Shack-Hartmann images were collected for each measurement. Each observer had three sets of measurements taken; the first and the second after careful alignment and the final after regrasping the bite bar in the same position as for the second measurement, but without pupil realignment. The modulation transfer functions for each set were calculated, and the effect of best-aligned custom treatments on the modulation transfer function was estimated. RESULTS: There were highly statistically significant differences in a large number of Zernike modes between the three sets of measurements. The modulation transfer functions calculated for the residual wavefronts after aligned custom treatment were below the diffraction limit. The root mean square wavefront errors were consistently better for the residual wavefronts obtained using the realigned data than using data taken without pupil realignment. CONCLUSIONS: Sequential measurement of ocular aberrations shows statistically significant differences in a large number of Zernike modes. If aberrations determined by a single measurement are to be used in a custom correction, the resulting modulation transfer function is likely to remain below the diffraction limit. Pupil realignment is critical in reduction of the residual root mean square wavefront values to a minimum.
Adult↗
Isocratic liquid chromatographic assay for monitoring the degradation of luteinizing hormone releasing hormone by extracts from the gastrointestinal tract of possums.
A simple HPLC method to separate human luteinizing hormone releasing hormone (LHRH) from its metabolites using an isocratic elution is described. Intact LHRH and five metabolites were separated in 11.4 min. The calibration curve (peak area versus concentration) was linear over the concentration range 1.25-35 microg/ml (r(2)=0.99) with the intercept not significantly different from zero (P>0.05). Intra-day and inter-day variability of the assay was less than 5% for repeat injections of 5, 14.5 and 29 microg/ml. The method was applied to evaluate the susceptibility of LHRH to enzymes present in the lumen and mucosal extracts of the gastrointestinal tract of possums. The major degradation products of LHRH were identified by HPLC separation, amino acid analysis and mass spectrometry as LHRH (1-5), LHRH (1-4), LHRH (1-3) and LHRH (3-4).
Animals↗