R. E. J. Ryder

Bio: R. E. J. Ryder is an academic researcher from University of Wales. The author has contributed to research in topics: Diabetic retinopathy & Ophthalmoscopy. The author has an hindex of 7, co-authored 12 publications receiving 409 citations. Previous affiliations of R. E. J. Ryder include University Hospital of Wales.

How soon after myocardial infarction should plasma lipid values be assessed

Abstract: Because acute myocardial infarction may affect plasma lipid concentrations it is commonly recommended that assessment of these concentrations should be delayed until about three months after the acute event. A study was therefore conducted of fasting plasma lipid concentrations in 58 patients with acute myocardial infarction. Measurements were made during their stay in hospital (days 1, 2, and 9) and three months later. Triglyceride concentrations remained unchanged throughout. Values of total cholesterol, low density lipoprotein, and high density lipoprotein all fell significantly between the first two days and day 9. Total cholesterol and low density lipoprotein also showed significant falls between days 1 and 2. Nevertheless, fasting plasma lipid concentrations showed no significant difference at any time during the first 48 hours from values measured three months later. After the infarction 26 patients changed to eating less fat or less energy, or both. More patients had hypercholesterolaemia in the first 48 hours than at three months. These results suggest that lipid state may be assessed as accurately, and possibly more accurately, during the first 48 hours after acute myocardial infarction than at three months.

Possible new method to improve detection of diabetic retinopathy: Polaroid non-mydriatic retinal photography.

Abstract: Two retinal cameras (Canon CR2 45NM and CR3 45NM) have recently become available and are capable of producing an instant colour photography of a 45 degree field of retina, including the macula and optic disc, without dilatation of the pupils being necessary. The ability of each camera to detect diabetic retinopathy was compared with that of doctors in diabetic clinics using ophthalmoscopy during busy clinic hours. The CR3 was found to be considerably superior to the CR2 in terms of quality of photograph because it can use a smaller pupil. Overall, the detection rate of the camera was more than four times higher than that of ophthalmoscopy through undilated pupils and more than twice as high as that of ophthalmoscopy through dilated pupils. Lesions missed by ophthalmoscopy but detected by the camera included soft exudates and circinate rings of hard exudates, sometimes encroaching on the macula. Though various aspects of this system of screening for diabetic retinopathy, in particular its ability to detect new retinal vessels, have not yet been assessed, the system may prove beneficial in the detection and monitoring of diabetic retinopathy.

Renal response to intravenous somatostatin in insulin-dependent diabetic patients and normal subjects.

Abstract: The acute effects of iv somatostatin (SRIH; 100 micrograms/h) on the urinary flow (Uvol), effective renal plasma flow (RPF), and glomerular filtration rate (GFR) were compared with those of a control infusion of 0.15 M NaCl in nine insulin-dependent diabetic (IDD) patients of less than 10 yr disease duration and six normal subjects (NS). RPF and GFR were measured using a standard primed constant isotope infusion of [125I]iodohippurate and [51Cr]chromium EDTA. Uvol, RPF, and GFR were measured during 20-min clearance periods. During the NaCl infusion mean Uvol, RPF, and GFR were 14.1 +/- 0.2 (+/- SEM), 708 +/- 4, and 150 +/- 1 mL/min in the IDD group and 12.7 +/- 0.4, 568 +/- 5, and 110 +/- 2 mL/min in the NS group, respectively. In the IDD patients Uvol, RPF, and GFR decreased from 16.6 +/- 1.8, 670 +/- 30, 146 +/- 4 mL/min pre-SRIH to 9.2 +/- 1 (P less than 0.001), 553 +/- 25 (P less than 0.001), and 130 +/- 5 (P less than 0.001) mL/min, respectively, at 120 min during the SRIH infusion. Similarly, in the NS group mean Uvol, RPF, and GFR were 14.2 +/- 0.6, 552 +/- 15, and 112 +/- 5 mL/min pre-SRIH and decreased to 7.4 +/- 0.6 (P less than 0.001), 422 +/- 7 (P less than 0.001), and 93 +/- 3 (P less than 0.001) mL/min, respectively, after 120 min of the SRIH infusion. SRIH, therefore, had a profound effect on renal function in both IDD patients and NS, resulting in a reduction in RPF, GFR, and, as a consequence, Uvol.

Effect of somatostatin on renal function

Abstract: Somatostatin has profound effects on both splanchnic and portal vascular beds. The effects of intravenous somatostatin (100 micrograms/h) on urinary volume, effective renal plasma flow, and glomerular filtration rate were compared with the effects of a control infusion of physiological saline in six normal subjects. Renal plasma flow and glomerular filtration rate were measured by primed constant isotope infusions of iodine-125 iodohippurate and chromium-51 edetic acid. Urinary volume, renal plasma flow, and glomerular filtration rate were measured during 20 minute clearance periods. During the control infusion urinary volume, renal plasma flow, and glomerular filtration rate remained essentially unchanged at 254 (SEM 3) ml/20 min, 568 (5) ml/min/1.73 m2, and 110 (2) ml/min/1.73 m2 respectively. From similar basal values the infusion of somatostatin led to a rapid decrease in all three variables. After 120 minutes of infusion of somatostatin urinary volume, renal plasma flow, and glomerular filtration rate were reduced to 148 (17) ml/20 min (p less than 0.01), 422 (7) ml/min/1.73 m2 (p less than 0.001), and 93 (3) ml/min/1.73 m2 (p less than 0.05) respectively. This effect on renal function should be borne in mind whenever somatostatin is used.

C reactive protein and its relation to cardiovascular risk factors: a population based cross sectional study.

Abstract: Objective: To test the hypothesis that minor chronic insults such as smoking, chronic bronchitis, and two persistent bacterial infections may be associated with increases in C reactive protein concentration within the normal range and that variations in the C reactive protein concentration in turn may be associated with levels of cardiovascular risk factors and chronic coronary heart disease. Design: Population based cross sectional study. Setting: General practices in Merton, Sutton, and Wandsworth. Subjects: A random sample of 388 men aged 50-69 years from general practice registers. 612 men were invited to attend and 413 attended, of whom 25 non-white men were excluded. The first 303 of the remaining 388 men had full risk factor profiles determined. Interventions: Measurements of serum C reactive protein concentrations by in house enzyme linked immunosorbent assay (ELISA); other determinations by standard methods. Coronary heart disease was sought by the Rose angina questionnaire and Minnesota coded electrocardiograms. Main outcome measures: Serum C reactive protein concentrations, cardiovascular risk factor levels, and the presence of coronary heart disease. Results: Increasing age, smoking, symptoms of chronic bronchitis, Helicobacter pylori and Chlamydia pneumoniae infections, and body mass index were all associated with raised concentrations of C reactive protein. C Reactive protein concentration was associated with raised serum fibrinogen, sialic acid, total cholesterol, triglyceride, glucose, and apolipoprotein B values. C Reactive protein concentration was negatively associated with high density lipoprotein cholesterol concentration. There was a weaker positive relation with low density lipoprotein cholesterol concentration and no relation with apolipoprotein A I value. C Reactive protein concentration was also strongly associated with coronary heart disease. Conclusion: The body9s response to inflammation may play an important part in influencing the progression of atherosclerosis. The association of C reactive protein concentration with coronary heart disease needs testing in prospective studies. Key messages Factors that determine levels of inflammatory mediators in the normal general population have not been explored, nor has their relation to cardio- vascular risk factors Among 50-69 year old men many environmental and lifestyle risk factors for cardiovascular disease are associated with raised serum concentrations of C reactive protein Circulating concentrations of lipids, glucose, and clotting factors are also associated with serum C reactive protein concentrations The body9s response to inflammation may influence the development of atherosclerosis

Use of methodological standards in diagnostic test research. Getting better but still not good

Abstract: Objective. —To determine the frequency and temporal changes in application of seven accepted methodological standards for the evaluation of diagnostic tests. Data Sources. —A search of the MEDLINE database yielded 1302 articles about diagnostic test studies, during a 16-year secular interval, 1978 through 1993, in four prominent general medical journals. Study Selection. —In the 112 eligible studies, the test was intended for clinical use, indexes of accuracy (sensitivity and specificity or likelihood ratios) were provided, and more than 10 patients were enrolled. Data Extraction. —Although each study was critically reviewed by one primary observer, a subset was independently evaluated for interrater consistency. Data Synthesis. —The percentage of studies that fulfilled criteria for each of the seven methodological standards are as follows: (1) specify spectrum of evaluated patients, 27%; (2) report test indexes for clinical subgroups, 8%; (3) avoid workup bias, 46%; (4) avoid review bias, 38%; (5) provide numerical precision for test indexes, 11%; (6) report frequency and management of indeterminate results when calculating test indexes, 22%; and (7) specify test reproducibility, 23%. Secular increases were found for six of the seven standards in ranges of use from 14% to 31% during 1978-1981 to 1990-1993. Nevertheless, only one standard, avoidance of workup bias, was fulfilled by more than 50% of studies in the most recent secular interval. Conclusions. —These results indicate that most diagnostic tests are still inadequately appraised. The routine demand for methodological standards could raise the quality of diagnostic test information, and the careful predissemination evaluation of diagnostic tests could eliminate useless tests before they receive widespread application. (JAMA. 1995;274:645-651)

Automatic detection of diabetic retinopathy using an artificial neural network : a screening tool

Abstract: AIMS: To determine if neural networks can detect diabetic features in fundus images and compare the network against an ophthalmologist screening a set of fundus images. METHODS: 147 diabetic and 32 normal images were captured from a fundus camera, stored on computer, and analysed using a back propagation neural network. The network was trained to recognise features in the retinal image. The effects of digital filtering techniques and different network variables were assessed. 200 diabetic and 101 normal images were then randomised and used to evaluate the network's performance for the detection of diabetic retinopathy against an ophthalmologist. RESULTS: Detection rates for the recognition of vessels, exudates, and haemorrhages were 91.7%, 93.1%, and 73.8% respectively. When compared with the results of the ophthalmologist, the network achieved a sensitivity of 88.4% and a specificity of 83.5% for the detection of diabetic retinopathy. CONCLUSIONS: Detection of vessels, exudates, and haemorrhages was possible, with success rates dependent upon preprocessing and the number of images used in training. When compared with the ophthalmologist, the network achieved good accuracy for the detection of diabetic retinopathy. The system could be used as an aid to the screening of diabetic patients for retinopathy.