Pupil Dilation May Affect Retinal Vessel Caliber Measures

Purpose: To assess the effect of pupil dilation on measures of retinal vessel caliber.

Design: Observational study with self-comparisons

Methods: Retinal photographs were taken for both eyes of 25 subjects before and after pupil dilation. Three photographic graders, masked to pupil dilation status, measured the same set of images using a computer-assisted, semi-automatic method. We compared means (standard deviations) of retinal arteriolar caliber equivalent (CRAE) and retinal venular caliber equivalent (CRVE) of the same eyes between pre- and post-dilation images. We assessed concordance correlation coefficients (CC), Bland Altman limits-of-agreements, and used linear mixed models to assess CRAE and CRVE measures associated with pupil dilation (influencing image quality), graders (observers) and right-left eye variation.

Results: We found high CCs for CRAE (0.82-0.94) and CRVE (0.87-0.94) between pre- and post-dilation images of the same eyes across the graders. Bland Altman plots showed that mean differences ranged from 0.55-3.42μm for CRAE and 1.56-2.29μm for CRVE. After adjusting for right-left eye random variation, a significant fixed effect of dilation was evident in mean CRAE in two of the three graders. There was no significant fixed effect of dilation in mean CRVE across all graders. In models including data of both eyes’ measures from pre- and post-dilation images by three graders, the fixed effect for dilation status contributed significantly to CRAE and CRVE variances whereas random effects for graders and dilation status contributed minimally.

Conclusions: Contrary to our hypothesis, we found a systematic effect of pupil dilation on retinal vessel caliber measures.     

Cost-effectiveness of counseling and pedometer use to increase physical activity in the Netherlands: a modeling study

Background

Counseling in combination with pedometer use has proven to be effective in increasing physical activity and improving health outcomes. We investigated the cost-effectiveness of this intervention targeted at one million insufficiently active adults who visit their general practitioner in the Netherlands.

Methods

We used the RIVM chronic disease model to estimate the long-term effects of increased physical activity on the future health care costs and quality adjusted life years (QALY) gained, from a health care perspective.

Results

The intervention resulted in almost 6000 people shifting to more favorable physical-activity levels, and in 5100 life years and 6100 QALYs gained, at an additional total cost of EUR 67.6 million. The incremental cost-effectiveness ratio (ICER) was EUR 13,200 per life year gained and EUR 11,100 per QALY gained. The intervention has a probability of 0.66 to be cost-effective if a QALY gained is valued at the Dutch informal threshold for cost-effectiveness of preventive intervention of EUR 20,000. A sensitivity analysis showed substantial uncertainty of ICER values.

Conclusion

Counseling in combination with pedometer use aiming to increase physical activity may be a cost-effective intervention. However, the intervention only yields relatively small health benefits in the Netherlands.     

Plasma protein turnover and tissue exchange; influence of dietary protein and protein depletion

The rate of plasma protein turnover is more rapid in dogs receiving adequate dietary protein than when a diet devoid of protein is fed. Both albumin and combined globulins are involved in this change. The difference in turnover is reflected in a total protein half-life of 4.8 days with protein feeding versus 7.8 days without protein in the diet and in the metabolism of 1.0 and 0.65 gm. per kilogram of body weight per day on the respective diets. Additions of dietary protein from 10 to 30 per cent caused no further increase in the rate of plasma protein turnover. With protein depletion due to plasmapheresis and a very low protein diet there is evidence of reduced protein metabolism as indicated by nitrogen retention as well as a reduction in total plasma protein breakdown and interchange of isotope between plasma and tissue proteins. Following introduction of labeled plasma protein into the circulation the net amount of isotope transferred to tissues has been computed from the difference between total plasma protein breakdown and combined C¹⁴ excretion in urine and expired air. In animals receiving adequate dietary protein, tissue transfer amounts to 70 per cent of the total lost from the plasma proteins each day while the percentage rises to 85 in depleted dogs deprived of protein. In dogs with both plasma and tissue proteins labeled it can be estimated that, under conditions of protein feeding, an amount of C¹⁴ approximately equal to that lost from the plasma must recycle to account for the observed decrease in Apparent plasma protein turnover rate, (t½ of 15 versus 5 days). Without protein in the diet the isotope contribution of the tissues to the maintenance of plasma protein levels must be as great as or greater than that transferred in the opposite direction.     

Creutzfeldt--Jakob Disease in Recipients of Human Growth Hormone in the United Kingdom: A Clinical and Radiographic Study

In the past 3 years there have been five further cases, in additionto one case reported in 1985, of Creutzfeldt-Jakob disease inrecipients of human growth hormone in the United Kingdom. Theclinical findings of two of these cases are described, demonstratinga typical presentation with a predominantly cerebellar syndromeat onset which is not commonly a presenting feature of sporadicCreutzfeldt-Jakob disease. In one case a ^99mTc hexamethylpropylenaminesingle photon emission tomographic scan showed marked impairmentof tracer uptake in the basal ganglia and cerebral cortex ata time when the clinical picture was predominantly cerebellar.This technique may be useful in early diagnosis. In the othercase post mortem examination of the brain showed prominent amyloiddeposition in the cerebellum, which has not been described previouslyin pituitary-hormone related Creutzfeldt-Jakob disease. Thepreviously published cases of growth hormone-related Creutzfeldt-Jakobdisease are reviewed and reasons for the particular clinicalpattern seen are discussed.