Self-reported oral health status, edentulism and all-cause mortality risk in 12 809 Australian older adults: a prospective cohort study

OBJECTIVE

To investigate the association between oral health status and all-cause mortality in older adults using prospective cohort study design.

SETTING AND PARTICIPANTS

In total, 12 809 adults aged ≥70 years (54.3% females) were participants of the ASPREE Longitudinal Study of Older Persons (ALSOP).

METHODS

Participants self-reported the presence of natural teeth and oral health status. The association of self-reported oral health, edentulism and the integrative measure of the two with all-cause mortality were explored using the Cox-regression models adjusted for age, gender, socio-economic status, health-related behaviours, weight status, aspirin and polypharmacy. Hazard ratios (HRs) and 95% confidence intervals (CIs) were reported.

RESULTS

In total, 22.2% of participants reported edentulism and 13.8% had fair/poor oral health. After adjustment for confounders, risk of all-cause mortality was higher among those with edentulism (vs. no edentulism) HR (95% CI) 1.43 (1.18, 1.73); and those with edentulism and reporting poor/fair oral health HR (95% CI) 1.69 (1.02, 2.82), or with no edentulism but reporting poor/fair oral health HR (95% CI) 1.46 (1.19-1.80) vs. no edentulism and reporting good/very good/excellent oral health. No association was observed between self-reported oral health alone and all-cause mortality.

CONCLUSIONS

The risk of all-cause mortality was 69% higher among older adults reporting both edentulism and poor/fair oral health compared with those with teeth and more favourable self-reported oral health. © 2023 Australian Dental Association.

Higher testosterone is associated with higher HDL-cholesterol and lower triglyceride concentrations in older women: an observational study

OBJECTIVE

This study aimed to determine whether concentrations of testosterone and its main precursor after menopause, dehydroepiandrosterone (DHEA), are associated with lipoproteins and other lipids in community-dwelling older women.

METHODS

The Sex Hormones in Older Women (SHOW) study was an observational study of 6358 Australian women, aged at least 70 years, with no prior major adverse cardiovascular event who had sex hormones measured by liquid chromatography-tandem mass spectrometry. Associations between hormones and lipids were examined using multilinear regression adjusted for potential confounders.

RESULTS

The cross-sectional analyses included 3231 participants, median age 74.0 (interquartile range 71.7-77.9) years. Compared with concentrations in the lowest quartile (Q1), testosterone concentrations in the highest quartiles (Q3 and Q4) were positively associated with high-density lipoprotein cholesterol (HDL-C) (p = 0.002 and p < 0.001, respectively) while Q4 testosterone concentrations were positively associated with total cholesterol (p = 0.038). Q2, Q3 and Q4 testosterone concentrations were significantly inversely associated with triglycerides (TG) (p = 0.024, p = 0.003 and p < 0.001, respectively). For DHEA, Q4 concentrations was positively associated with non-HDL-C (p = 0.024).

CONCLUSIONS

In older women, higher endogenous testosterone concentrations are significantly associated with higher HDL-C and lower TG, indicating a less atherogenic profile. These findings suggest a neutral, or potentially protective, cardiovascular disease effect of testosterone in older women.

Compliance-Adjusted Estimates of Aspirin Effects Among Older Persons in the ASPREE Randomized Trial

The Aspirin in Reducing Events in the Elderly (ASPREE) Trial recruited 19,114 participants across Australia and the United States during 2010-2014. Participants were randomized to receive either 100 mg of aspirin daily or matching placebo, with disability-free survival as the primary outcome. During a median 4.7 years of follow-up, 37% of participants in the aspirin group permanently ceased taking their study medication and 10% commenced open-label aspirin use. In the placebo group, 35% and 11% ceased using study medication and commenced open-label aspirin use, respectively. In order to estimate compliance-adjusted effects of aspirin, we applied rank-preserving structural failure time models. The results for disability-free survival and most secondary endpoints were similar in intention-to-treat and compliance-adjusted analyses. For major hemorrhage, cancer mortality, and all-cause mortality, compliance-adjusted effects of aspirin indicated greater risks than were seen in intention-to-treat analyses. These findings were robust in a range of sensitivity analyses. In accordance with the original trial analyses, compliance-adjusted results showed an absence of benefit with aspirin for primary prevention in older people, along with an elevated risk of clinically significant bleeding.

The relationship between long-term blood pressure variability and cortical thickness in older adults

High blood pressure variability (BPV) is a risk factor for cognitive decline and dementia, but its association with cortical thickness is not well understood. Here we use a topographical approach, to assess links between long-term BPV and cortical thickness in 478 (54% men at baseline) community dwelling older adults (70-88 years) from the ASPirin in Reducing Events in the Elderly NEURO sub-study. BPV was measured as average real variability, based on annual visits across three years. Higher diastolic BPV was significantly associated with reduced cortical thickness in multiple areas, including temporal (banks of the superior temporal sulcus), parietal (supramarginal gyrus, post-central gyrus), and posterior frontal areas (pre-central gyrus, caudal middle frontal gyrus), while controlling for mean BP. Higher diastolic BPV was associated with faster progression of cortical thinning across the three years. Diastolic BPV is an important predictor of cortical thickness, and trajectory of cortical thickness, independent of mean blood pressure. This finding suggests an important biological link in the relationship between BPV and cognitive decline in older age.

Sex hormones, SHBG and cognitive performance among older Australian women: an observational study

OBJECTIVE

This study aims to explore the associations between sex hormones and cognitive performance in older women.

METHODS

Associations between sex hormones, sex hormone binding globulin (SHBG) and cognitive performance were examined in women aged at least 70 years, without dementia and not using medications that influence sex hormones. Linear and generalized linear regression models included age, body mass index, education, smoking, alcohol, living circumstances, diabetes, hypertension, depression and impaired renal function.

RESULTS

The included 5511 women had a median (interquartile range) age of 73.9 (71.6-77.6) years. No associations were found for estrone, estradiol, testosterone or dehydroepiandrosterone and cognitive performance. SHBG concentrations above quartile 1 (Q1) were significantly inversely associated with processing speed (Q2, β = -0.94, 95% confidence interval [CI] - 1.64 to -0.24, p = 0.009; Q3, β = -0.82, 95% CI -1.53 to -0.10, p = 0.025; and Q4, β = -0.95, 95% CI -1.70 to -0.20, p = 0.013).

CONCLUSIONS

Sex hormones were not associated with cognitive performance. The finding that low SHBG is associated with better processing speed warrants further investigation. The null findings for the sex hormones establish a firm baseline to confidently explore the association between sex hormones and longitudinal cognitive performance in this population.

TRIAL REGISTRATION

International Standard Randomized Controlled Trial Number Register (ISRCTN83772183) and ClinicalTrials.gov (NCT01038583).

The Association between Metabolic Syndrome, Frailty and Disability-Free Survival in Healthy Community-dwelling Older Adults

OBJECTIVES

To examine the association between metabolic syndrome (MetS) and frailty, and determine whether co-existent MetS and frailty affect disability-free survival (DFS), assessed through a composite of death, dementia or physical disability.

DESIGN

Longitudinal study.

SETTING AND PARTICIPANTS

Community-dwelling older adults from Australia and the United States (n=18,264) from "ASPirin in Reducing Events in the Elderly" (ASPREE) study.

MEASUREMENTS

MetS was defined according to American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines (2018). A modified Fried phenotype and a deficit accumulation Frailty Index (FI) were used to assess frailty. Association between MetS and frailty was examined using multinomial logistic regression. Cox regression was used to analyze the association between MetS, frailty and DFS over a median follow-up of 4.7 years.

RESULTS

Among 18,264 participants, 49.9% met the criteria for MetS at baseline. Participants with Mets were more likely to be pre-frail [Relative Risk Ratio (RRR): 1.22; 95%Confidence Interval (CI): 1.14, 1.30)] or frail (RRR: 1.66; 95%CI: 1.32, 2.08) than those without MetS. MetS alone did not shorten DFS while pre-frailty or frailty alone did [Hazard Ratio (HR): 1.68; 95%CI: 1.45, 1.94; HR: 2.65; 95%CI:1.92, 3.66, respectively]. Co-existent MetS with pre-frailty/frailty did not change the risk of shortened DFS.

CONCLUSIONS

MetS was associated with pre-frailty or frailty in community-dwelling older individuals. Pre-frailty or frailty increased the risk of reduced DFS but presence of MetS did not change this risk. Assessment of frailty may be more important than MetS in predicting survival free of dementia or physical disability.

Self-Reported Early and Later Life Weight and the Risk of All-Cause Mortality in Older Adults

OBJECTIVES

The extent to which body weight in early adulthood is associated with late-life mortality risk is unclear. This study aimed to determine the association between body mass index (BMI) in early adulthood (at 18 years of age) and older age (70 years and over), and the risk of mortality in later life.

DESIGN

Secondary analysis of the ASPREE Longitudinal Study of Older Persons (ALSOP).

SETTING, PARTICIPANTS

Data were from 14,853 relatively healthy community-dwelling Australians aged ≥ 70 years when enrolled in the study.

MEASUREMENTS

Self-reported weight at age ≥ 70 years and recalled weight at age 18 years were collected at ALSOP study baseline. Height was measured with a stadiometer and was used for calculation of BMI at both timepoints. BMI at each timepoint was defined as: underweight, normal weight, overweight and obese. Individuals were categorised into one of five 'lifetime' BMI groups: normal weight (BMI between 18.5 and 24.9 at both times), overweight (25.0-29.9 at either or both times), obesity to non-obese (≥30.0 at age 18 and <30.0 ≥ 70 years), non-obese to obesity (<30.0 at age 18 and ≥30.0 at age ≥ 70 years), and early and later life obesity (≥30.0 at both times).

RESULTS

During a median 4.7 years follow-up, 715 deaths occurred. Obesity at 18 years, but not in older age (p=0.44), was significantly associated with the risk of mortality in later life, even after accounting for current health status (HR: 2.35, 95% CI: 1.53-3.58, p<0.001). Compared with participants with normal BMI at both time points, being obese at both time points was associated with increased mortality risk (HR=1.99, 95% CI: 1.04-3.81, p=0.03), and the risk was even greater for individuals who were obese at 18 years but were no longer obese in older age (HR=2.92, 95% CI: 1.65-5.16, p<0.001), in fully adjusted models. Participants who were normal weight at 18 years and were obese in later life, did not have an increased mortality risk (p=0.78).

CONCLUSIONS

Obesity in early adulthood, and obesity in both early and later life, were associated with increased mortality risk in later life. This highlights the importance of preventing obesity in early adulthood and maintaining a normal weight over an adult lifespan.

Correlates of Meal Skipping in Community Dwelling Older Adults: A Cross-Sectional Study

In this cross-sectional analysis of 10,071 community dwelling adults aged ≥70 years, we examined factors associated with meal skipping (self-reported) using multivariable logistic regression. Prevalence of meal skipping in this study was 19.5%. The adjusted odds (aOR [95%CI]) of meal skipping were lower in those 85+ years (vs. 70-74.9 years, 0.56 [0.45-0.70]), and in those in regional areas (vs. urban area, 0.81 [0.72-0.92]). Higher odds of meal skipping were observed for those living alone (vs. living with someone, 1.84 [1.64-2.05]), current smokers (vs. non-smokers, 2.07 [1.54-2.80]), consumers of high amounts of alcohol (vs. abstainers 1.93 [1.35-2.75]), those with poor oral health (vs. excellent oral health, 1.71 [1.07 -2.73]) diabetes (vs. not 1.26 [1.06-1.50]), or frailty (vs. not, 1.63 [1.09-2.43]). This study identified socio-demographic, social, behavioural and biomedical correlates of meal skipping in later life, which may assist in targeting interventions to address meal skipping.

Erratum: The Association Between Frailty and All-Cause Mortality in Community-Dwelling Older Individuals: An Umbrella Review

The original version of this article unfortunately contained a mistake. Appendix II was published twice in the supporting information. The original publication has been updated. Appendix I and Appendix II are now both available in the online publication.

The Association between Frailty and All-Cause Mortality in Community-Dwelling Older Individuals: An Umbrella Review

Frailty is associated with multiple adverse health outcomes, including mortality. Several methods have been used to characterize frailty, each based on different frailty scales. These include scales based on phenotype, multidomain, and deficit accumulations. Several systematic reviews have examined the association between frailty and mortality; however, it is unclear whether these different frailty scales similarly predict mortality. This umbrella review aims to examine the association between frailty assessed by different frailty scales and all-cause mortality among community-dwelling older adults. A protocol was registered at PROSPERO, and it was conducted following the PRISMA statement. MEDLINE, Embase, PubMed, Cochrane Database of Systematic Reviews, Joanna Briggs Institute (JBI) EBP database, and Web of Science database was searched. Methodological quality was assessed using the JBI critical appraisal checklist and online AMSTAR-2 critical appraisal checklist. For eligible studies, essential information was extracted and synthesized qualitatively. Five systematic reviews were included, with a total of 434,115 participants. Three systematic reviews focused on single frailty scales; one evaluated Fried's physical frailty phenotype and its modifications; another focused on the deficit accumulation frailty index. The third evaluated the FRAIL (Fatigue, Resistance, Ambulation, Illness, and Loss of weight) scale. The two other systematic reviews determined the association between frailty and mortality using different frailty scales. All of the systematic reviews found that frailty was significantly associated with all-cause mortality. This umbrella review demonstrates that frailty is a significant predictor of all-cause mortality, irrespective of the specific frailty scale.

Accelerated Epigenetic Aging in Peripheral Blood does not Predict Dementia Risk

BACKGROUND

There is strong evidence that epigenetic age acceleration is associated with increased risk of later-life diseases and all-cause mortality. However, there is currently limited evidence that suggests accelerated epigenetic age is associated with dementia risk.

OBJECTIVE

This study aims to clarify whether epigenetic biomarkers of accelerated aging can predict dementia risk, which is an important consideration as aging is the greatest risk factor for the disease.

METHODS

DNA methylation was measured in peripheral blood samples provided by 160 participants from the ASPirin in Reducing Events in the Elderly study, including 73 pre-symptomatic dementia cases and 87 controls matched for age, sex, and smoking and education status. Epigenetic age was calculated using Horvath, Hannum, GrimAge and PhenoAge DNA methylation clocks, and age acceleration (the disparity between chronological age and epigenetic age) was determined.

RESULTS

There was no difference in age acceleration between dementia cases and controls. In males, only Hannum's intrinsic epigenetic age acceleration was increased in pre-symptomatic dementia cases compared to controls (Δ +1.8 years, p = 0.03).

CONCLUSION

These findings provide no strong evidence that accelerated epigenetic aging measured in peripheral blood can predict dementia risk.

P4557Factors associated with treatment and control of hypertension in a healthy elderly population free of cardiovascular disease: a cross-sectional study

Introduction

Despite readily available treatments, control of high blood pressure (BP) in the ageing population remains suboptimal. Gaps in understanding the management of high BP amongst the elderly exist, as most studies have been in predominantly middle-aged populations.

Purpose

We explored pharmacological BP lowering treatment and control among elderly hypertensive participants free from overt cardiovascular disease (CVD), and identified factors related to both “untreated” and “treated but uncontrolled” high BP.

Methods

We analyzed baseline data from 19,114 individuals aged ≥65 years enrolled from Australia and the US in the ASPirin in Reducing Events in the Elderly (ASPREE) study. Hypertension was defined as an average systolic/diastolic BP ≥140/90 mmHg and/or use of any BP-lowering medication. `Controlled hypertensives” were those receiving BP-lowering medication and with BP <140/90 mmHg. Descriptive analyses were used to summarize hypertension control rates; logistic regression was used to investigate relationships with treatment and BP control.

Results

Overall, 74% (14,213/19,114) of participants were hypertensive, and of these 29% (4,151/14,213) were untreated. Among those treated, 47% (4,732/10,062) had BP <140/90 mmHg. Participants who were untreated were more likely to be men, have higher educational status, and be in good physical health, and less likely to have significant comorbidities. The factors related to “treated but uncontrolled” hypertension included older age, being men, Black race (versus White), using BP lowering monotherapy and residing in Australia (versus US) (Figure 1).

Conclusion(s)

There were high levels of “untreated” and “treated but uncontrolled” BP, in an otherwise healthy elderly population, suggesting that opportunities for better BP control exist through targeting intervention to high-risk individuals.

Acknowledgement/Funding

National Institute on Aging and the National Cancer Institute at NIH; NHMRC Australia, Monash University, Victorian Cancer Agency (Australia)

P6362Impact of the 2017 AHA/ACC hypertension guideline on hypertension prevalence and cardiovascular risk factors in a healthy older cohort

Background

The 2017 American Heart Association (AHA)/American College of Cardiology (ACC) hypertension guideline recommends a target blood pressure (BP) of <130/80 mmHg regardless of age, which is lower than previously recommended BP goals.

Purpose

We aimed to determine how much the updated classification for high BP would increase the overall prevalence of “hypertension” in an otherwise healthy elderly population. Additionally, we explored the cardiovascular disease (CVD) risk factor distribution in those newly classified “hypertensives” to determine whether the increased prevalence of hypertension was accompanied by an increase in other modifiable CVD risk factors.

Methods

We used baseline data from 19,114 participants (16,703 in Australia and 2,411 in the USA) aged ≥65 years who were enrolled in the ASPirin in Reducing Events in the Elderly (ASPREE) study between 2010 and 2014. Participants were classified as having hypertension using either: (a) pre-2017 thresholds (SBP ≥140 mmHg or mean DBP ≥90 mmHg and/or on anti-hypertensive) or (b) 2017 AHA/ACC guidelines (SBP ≥130 mmHg or DBP ≥80 mmHg and/or on anti-hypertensive). We assessed the presence of cardiovascular disease risk factors such as diabetes, hypercholesterolemia, smoking, obesity, reduced renal function among these hypertensive participants and also estimated their predicted risk over 10 years.

Results

Based on pre-2017 thresholds, 74% of the participants met the criteria for hypertension. Hypertension prevalence increased to 87% when the more stringent 2017 guideline was applied. 29% of this subset of newly classified hypertensive participants did not have any other identifiable traditional CVD risk factors. Further, a significantly lower 10-year predicted cardiovascular risk (22% versus 26%, p<0.001) among those newly classified hypertensive participants was observed in relation to those having hypertension based on pre-2017 guideline (Figure 1).

Figure 1. 10-year predicted CVD risk among hyoertensive and newly classified hypertensive ASPREE participants by presence of CVD risk factor

Conclusion

As expected, the prevalence of hypertension increased among the healthy elderly when applying the new AHA-2017 guideline; however, the increased prevalence occurs despite lack of an accompanying increase in additional CVD risk factors or predicted 10-year risk. Our findings suggest an individualized approach is needed in evaluating high BP among the healthy elderly.

Acknowledgement/Funding

National Institute on Aging and the National Cancer Institute at NIH; NHMRC Australia, Monash University, Victorian Cancer Agency (Australia)

Effect of systemic B-type natriuretic peptide on cardiac vagal motoneuron activity

Intravenous B-type natriuretic peptide (BNP) enhances the bradycardia of reflexes from the heart, including the von Bezold-Jarisch reflex, but its site of action is unknown. The peptide is unlikely to penetrate the blood-brain barrier but could act on afferent or efferent reflex pathways. To investigate the latter, two types of experiment were performed on urethane-anesthetized (1.4 g/kg iv) rats. First, the activity was recorded extracellularly from single cardiac vagal motoneurons (CVMs) in the nucleus ambiguus. CVMs were identified by antidromic activation from the cardiac vagal branch and by their barosensitivity. Phenyl biguanide (PBG), injected via the right atrium in bolus doses of 1-5 mug to evoke the von Bezold-Jarisch reflex, caused a dose-related increase in CVM activity and bradycardia. BNP infusion (25 pmol.kg(-1).min(-1) iv) significantly enhanced both the CVM response to PBG (n = 5 rats) and the reflex bradycardia, but the log-linear relation between those two responses over a range of PBG doses was unchanged by BNP. The reflex bradycardia was not enhanced in five matched time-control rats receiving only vehicle infusions. In five other rats the cervical vagi were cut and the peripheral right vagus was stimulated supramaximally at frequencies of 1-20 Hz. The bradycardic responses to these stimuli were unchanged before, during, and after BNP infusion. We conclude that systemic BNP in a moderate dose enhances the von Bezold-Jarisch reflex activation of CVM, in parallel with the enhanced reflex bradycardia. That enhancement is due entirely to an action before the vagal efferent arm of the reflex pathway.

How red is a white eye? Clinical grading of normal conjunctival hyperaemia

PURPOSE

To quantify the level of normal bulbar conjunctival hyperaemia using the Cornea and Contact Lens Research Unit (CCLRU) grading scale, and to investigate inter-observer agreement.

METHODS

Bulbar conjunctival hyperaemia was assessed by two trained observers, using the CCLRU grading scale (zero to four units) interpolated into 0.1 increments, on the right eye of 121 healthy, non-contact lens-wearing subjects (male=58, female=63, median age=28 years, range 16-77). The eye was observed using a slit-lamp bio-microscope (x 10 magnification) under diffuse, white illumination. The subject's position of gaze was directed to allow grading of four quadrants: superior, nasal, inferior, and temporal conjunctiva. Bulbar redness was defined as the average of those four grades of conjunctival hyperaemia. A further twenty subjects were recruited to assess inter-observer agreement (male=8, female=12, median age=23 years).

RESULTS

The average bulbar redness was 1.93 (+/-0.32 SD) units. The nasal (2.3+/-0.4) and temporal (2.1+/-0.4) quadrants were significantly redder than the superior (1.6+/-0.4) and inferior (1.7+/-0.4) quadrants (P<0.0001). Males had redder eyes than females by 0.2 units. Inter-observer 95% limits of agreement for bulbar redness was 0.38 units.

CONCLUSIONS

The average bulbar redness of 1.9 units was higher than expected, reflecting the design of the grading scale. A bulbar redness of greater than 2.6 units may be considered abnormal, and a change in bulbar redness of > or =0.4 units may be significant.

Differential effects of aging on fluid intake in response to hypovolemia, hypertonicity, and hormonal stimuli in Munich Wistar rats

A significant proportion of aged humans may have impaired thirst and inadequate fluid intake after a period of fluid deprivation. We have studied the water drinking responses, relative to body weight, of Munich Wistar (MW) rats in response to osmotic, hypovolemic, dehydrational, and angiotensin (Ang)-related stimuli as they aged from 3 to 24 months. Young 3-months-old (m.o.) rats had the largest daily fluid intakes and drinking responses to hypertonic and dehydrational stimuli, suggesting that they have accentuated thirst in comparison with older age groups. There were no differences in daily fluid intake from 6-24 m.o.; however, drinking responses to i.p. injection of hypertonic 0.4 mol/liter NaCl gradually declined over this period so that in 24-m.o. rats the response was only half that of 6-m.o. rats. Water intake after 24-h water deprivation also declined gradually over 24 months. Drinking responses to hypovolemia induced by s.c. injection of colloid (polyethylene glycol) were unchanged in 6- to 15-m.o. rats, then declined precipitously in 18- to 24-m.o. rats. Drinking responses to s.c. Ang II or s.c. isoproterenol were not reduced in 24-m.o. rats, nor was the drinking associated with feeding. Therefore, there are specific impairments of water intake in response to hypertonicity and hypovolemia in aged MW rats, but Ang-related drinking is not reduced. Like aged humans, aged MW rats exhibit high plasma atrial natriuretic peptide levels and impaired cardiovascular reflexes that could contribute to the impairment of thirst with age.

Economic costs of cataract surgery using a rigid and a foldable intraocular lens

Optimal delivery of healthcare requires consideration of various costs. A foldable intraocular lens (IOL) is more expensive than an equivalent rigid IOL. However, surgical and post-operative costs may make a foldable IOL economically preferable. We compared the economic costs of cataract surgery plus implantation of a foldable IOL with implantation of a rigid IOL. Prospective audit of the clinical records of 82 pseudophakes; 39 implanted with a rigid IOL and 43 implanted with a foldable IOL by one surgeon. Average follow-up periods were 25 +/- 7 months and 23 +/- 5 months respectively. There was no difference between the two groups for the follow-up period (P = 0.55), number of post-operative complications (P = 0.25) or cost of post-operative visits (P = 0.83). The cost of single-use theatre equipment was greater for the rigid-IOL group (P= 0.0001). The total identified cost per patient was greater for the foldable-IOL group (P = 0.0001). Despite possible technical advantages, implantation of the foldable IOL did not provide an economic benefit, either in the initial cost or in the costs of post-operative care. Over the 2-year period, implanting with the rigid IOL cost, on average, Pound Sterling57 less per patient. Despite this economic difference, a cost-benefit analysis is required, since other factors may be more important.

Eye movements and reading with large print and optical magnifiers in macular disease

PURPOSE

Reading rate has been the main performance measure in studies that have compared reading with large print and optical magnifiers; eye movement characteristics have not been considered. We compared both eye movement characteristics and reading rates for subjects with macular disease reading without and with a range of low-vision devices.

METHODS

Silent reading rate and eye movement characteristics for text passages at critical print size of 21 subjects aged 14 to 88 years with macular disease were measured with and without their preferred low-vision device. Saccadic frequency was determined from a sequencing task comprising five letters each separated by 5 degrees. Eye movements were recorded using an infrared limbal reflection system.

RESULTS

There were no significant differences in reading rate, fixation durations, saccade numbers per word, or percent retrace time when using a low-vision device compared with reading without a low-vision device. The percentage of regressions was, however, lower with the low-vision device. Saccadic frequency in the sequencing task was predictive of reading performance with and without a low-vision device.

CONCLUSIONS

When reading at critical print size, in terms of reading rate or saccades per word, there was no advantage to using large print over an optical low-vision device.

Effects of intravenous brain natriuretic peptide on regional sympathetic activity in patients with chronic heart failure as compared with healthy control subjects

OBJECTIVES

We sought to assess the effects of brain natriuretic peptide (BNP) on systemic and regional sympathetic nervous activity (SNA) in both patients with congestive heart failure (CHF) and healthy control subjects.

BACKGROUND

Although the response of SNA to atrial natriuretic peptide (ANP) has been well documented, the response of SNA to BNP is largely unknown.

METHODS

We assessed cardiac and whole-body SNA using the norepinephrine (NE) tracer dilution method before and after infusion of two doses of BNP (3 and 15 ng/kg body weight per min) in 11 patients with stable CHF (ejection fraction 24 +/- 2%) and 12 age-matched healthy control subjects. In addition, renal SNA and hemodynamic variables were assessed at baseline and after the higher BNP dose.

RESULTS

Low dose BNP did not change blood pressure or whole-body NE spillover, but reduced cardiac NE spillover in both groups by 32 +/- 13 pmol/min (p < 0.05). In both groups, high dose BNP reduced pulmonary capillary pressure by 5 +/- 1 mm Hg (p < 0.001) and mean arterial pressure by 6 +/- 3 mm Hg (p < 0.05), without a concomitant increase in whole-body NE spillover; however, cardiac NE spillover returned to baseline levels. Renal NE spillover remained virtually unchanged in healthy control subjects (501 +/- 120 to 564 +/- 115 pmol/min), but was reduced in patients with CHF (976 +/- 133 to 656 +/- 127 pmol/min, p < 0.01).

CONCLUSIONS

Our results demonstrate a sympathoinhibitory effect of BNP. Cardiac sympathetic inhibition was observed at BNP concentrations within the physiologic range, whereas high dose BNP, when arterial and filling pressures fell and reflex sympathetic stimulation was expected, systemic and cardiac SNA equated to baseline values. There was inhibition of renal SNA in patients with CHF, but not in healthy control subjects. Whether this effect is specific to BNP or related to reduced filling pressure remains to be determined.

ANP, BNP, and CNP enhance bradycardic responses to cardiopulmonary chemoreceptor activation in conscious sheep

We demonstrated previously that atrial natriuretic peptide (ANP) enhances reflex bradycardia to intravenous serotonin [5-hydroxytryptamine (5-HT)] (von Bezold-Jarisch reflex) in rats. To determine whether 1) ANP affects this cardiopulmonary vagal reflex in another species and 2) B-type (BNP) and C-type (CNP) natriuretic peptides share with ANP the ability to modulate this reflex, we used intravenous phenylbiguanide (PBG), a 5-HT(3) agonist, as the stimulus to evoke a von Bezold-Jarisch reflex (dose-related, reproducible bradycardia) in conscious adult sheep (n = 5). Three doses of PBG (13 +/- 3, 20 +/- 3, and 31 +/- 4 microg/kg) injected into the jugular vein caused reflex cardiac slowing of -7 +/- 1, -15 +/- 2, and -36 +/- 3 beats/min, respectively, under control conditions. These doses of PBG were repeated during infusions of ANP, BNP, or CNP (10 pmol. kg(-1). min(-1) iv), or vehicle (normal saline). Each of the natriuretic peptides significantly (P < 0.05) enhanced the sensitivity of bradycardic responses to PBG by 94 +/- 8% (ANP), 142 +/- 55% (BNP), and 61 +/- 16% (CNP). Thus not only did ANP sensitize cardiopulmonary chemoreceptor activation in a species with resting heart rate close to that in humans, but BNP and CNP also enhanced von Bezold-Jarisch reflex activity in conscious sheep.

Clinical grading of the upper palpebral conjunctiva of non-contact lens wearers

PURPOSE

To categorize the appearance of the normal upper palpebral conjunctiva using a grading scale and to investigate interobserver agreement with a grading scale modified to include decimal increments.

METHODS

Upper palpebral conjunctival appearance of 96 non-contact lens wearing subjects aged 18 to 75 years was assessed using a photographic grading scale that has a generic (zero to four) scale to score redness and roughness of the palpebral conjunctiva.

RESULTS

Median redness and roughness was about 1.25 units. About 5% of subjects had redness or roughness >2.0 units. Interobserver agreement improved during the study. By the end of the study, the standard deviation of the discrepancy scores was 0.12 to 0.19 units.

CONCLUSIONS

Upper palpebral conjunctival redness or roughness >2.0 units are unusual. The grading scale can be used successfully with decimal rather than integer scale increments. For experienced clinicians, a change in grade of > or =0.5 units may be significant.

Clinical grading of corneal staining of non-contact lens wearers

To distinguish normal from pathological corneal fluorescein staining requires knowledge of background levels of staining among otherwise healthy individuals. Corneal staining of 102 non-contact lens wearing subjects was assessed using a photographic grading scale that uses a generic (0 to 4) scale to score corneal staining. Some degree of corneal staining was found on 79% of the corneas. Low inter-observer variability suggests that the corneal staining grading scale can be used successfully with decimal rather than integer scale increments.

Measuring contrast sensitivity with inappropriate optical correction

Spatial frequency-selective minima (notches) in the contrast sensitivity function (CSF) because of defocus can mimic those that occur with ocular disease. We examined the influence of measurement conditions on CSF shape in simulated clinical testing. CSF notches occurred with almost all levels of defocus for all subjects. Multiple notches were found under some conditions. Notches were found with defocus as small as 0.50 D. Effects of induced astigmatism depended on the orientation of the target. Notches were apparent in defocus conditions after stimulus size and room illuminance were modified and when subjects had insufficient accommodation to compensate for hypermetropic defocus. The equivalent of notches was not noted with the Pelli-Robson chart. As defocus-induced CSF notches may be mistaken for functional loss, careful refractive correction should be conducted prior to clinical or experimental CSF measurement, even at low spatial frequencies.

Oral and silent reading performance with macular degeneration

Previous studies have shown that reading rate for very large print (6 degrees, 1.86 logMAR character size) is a strong predictor of oral reading rate with low vision devices (LVDs). We investigated whether this would apply using large print sizes more readily available in clinical situations (e.g. 2 degrees, 1.4 logMAR), for subjects with macular degeneration. We assessed rauding rates--reading for understanding. A combination of near word visual acuity and large print reading rate (without LVDs) provided the best prediction of oral rauding rates (with LVDs). However, near word visual acuity alone was almost as good. Similarly, silent rauding rate was predicted best by near word visual acuity alone. We give near visual acuity limits as a clinical guide to expected oral and silent reading performance with LVDs for patients with macular degeneration.

Type-C natriuretic peptide prevents development of experimental atherosclerosis in rabbits

1. We investigated the effect of local administration of type-C natriuretic peptide (CNP) on the endothelial dysfunction and development of an atheroma-like neointima induced by a peri-arterial collar in rabbits. 2. Peri-arterial collars were placed on both common carotid arteries allowing local treatment of the collared region with either CNP (10 micromol/L) or saline. After 7 days, uncollared (control) and collared sections were taken from both arteries for pharmacological and morphological analysis. 3. Application of the collar markedly attenuated (P < 0.05) endothelium-dependent vasorelaxation induced by acetylcholine (ACh); inhibition of 5-hydroxytryptamine contraction was 80+/-5% in control sections compared with 44+/-4% in collared sections from the same arteries. Local infusion of CNP (10 micromol/L) into the collar restored ACh-induced vasorelaxation (74+/-3% from collared arteries + CNP vs 77+/-2% from control sections from the same arteries). 4. Type-C natriuretic peptide treatment also reduced (P < 0.05) intimal thickening compared with contralateral collared arteries (intima/media ratio 0.06+/-0.01 vs 0.16+/-0.01). 5. These results provide evidence that locally administered CNP is effective in preventing the endothelial dysfunction and development of a neointima in this model.

Effects of defocus and pupil size on human contrast sensitivity

Defocus lowers the contrast sensitivity function (CSF), producing a complex function with local dips and peaks. Previously, we were able to predict the shape of the CSF with large pupils from measured transverse aberrations with hypermetropic defocus but not with myopic defocus (Atchison et al., 1998c, J. Opt. Soc. Am. A. 15, 2536). As there is no reason that myopic defocus should be more difficult to predict than hypermetropic defocus, we modified the procedure to try to improve CSF predictions with myopic defocus. Also, we extended the study to consider a range of pupil sizes. CSFs were measured for three subjects at three defocus levels (in-focus, -2D and +2D) and three pupil sizes (2 mm, 4 mm and 6 mm). Using a diffraction optics model, transverse aberration measures and in-focus CSF measures, we predicted the defocused CSFs. The predicted defocused CSFs were lower than the in-focus CSF as expected, and had complex shapes that varied with defocus and pupil size and between subjects. While a few predictions were poor, generally, the overall magnitude and shape of the defocused CSFs were well predicted and similarly so for myopic and hypermetropic defocus. Some further improvements in technique are indicated.

Similar baroreflex bradycardic actions of atrial natriuretic peptide and B and C types of natriuretic peptides in conscious rats

OBJECTIVE

We have previously shown that atrial natriuretic peptide (ANP) modulates cardiac barosensitive afferent pathways to enhance reflex bradycardia in rats. The present study examined whether B-type natriuretic peptide (BNP) and C-type natriuretic peptide (CNP) also modulate heart rate reflex function.

DESIGN

Baroreflex bradycardia was evoked by rapid (over 4-6 s) intravenous (i.v.) infusions of methoxamine (100 microg/kg; 'ramp' baroreflex technique) in the presence of infused i.v. natriuretic peptide and of vehicle (0.9% saline, 270 microl/h) in conscious adult Munich-Wistar rats. Initially a dose-response study to ANP (infused at 25, 50 and 100 pmol/kg per min i.v.) was performed in 10 rats to determine an appropriate dose for subsequent experiments with the other peptides. In a separate group of 11 animals, rat BNP-32 and rat CNP-22 were infused at 50 pmol/kg per min i.v.

RESULTS

Reflex responses to ANP were dose-related, with a significant increase in baroreflex sensitivity of 50+/-15% at the 25 pmol dose, 102+/-10% at the 50 pmol dose and 117+/-11% at 100 pmol dose (all P<0.05). BNP and CNP (50 pmol/kg/min i.v.) substantially increased baroreflex bradycardia (by 115+/-17% and 62+/-15%, respectively; P<0.05) compared to vehicle infusion.

CONCLUSIONS

Both BNP and CNP augmented baroreflex slowing of heart rate in response to rapid increases in blood pressure in rats. Whereas other reports have shown marked differences in cardiovascular responses between the natriuretic peptides, particularly with CNP, our findings demonstrate an important common action of ANP, BNP and CNP to facilitate vagal heart rate baroreflexes.

A comparison of visual performance between a rigid PMMA and a foldable acrylic intraocular lens

PURPOSE

To examine post-operative visual outcomes when using micro-incision surgery and a three-piece, foldable acrylic intraocular lens (IOL) and when using small-incision surgery and a one-piece, rigid polymethyl-methacrylate (PMMA) IOL.

METHODS

Phacoemulsification and IOL implantation was conducted by one surgeon on 86 subjects (aged 50-89 years) with cataracts. Of these subjects, 67 completed the study. Subjects were implanted either with a foldable IOL (n = 38) or a rigid IOL (n = 29). Best corrected Snellen visual acuity and contrast sensitivity (2-28 cycles/degree) were measured approximately 2 months post-operatively. Comparisons were made between the pseudophakic groups and an additional group of 28 age-matched, normal subjects (aged 58-81 years). Non-parametric (Kruskal-Wallis and Mann-Whitney U) as well as parametric (ANOVA and Pearson) statistics tests were used in the analysis of results.

RESULTS

All pseudophakes had corrected visual acuity of 6/9 or better. There were no significant differences in visual acuity (Kruskal-Wallis, p = 0.61) or contrast sensitivity (ANOVA, p = 0.33) between the three groups. The mean residual refractive error of the foldable IOL group was hypermetropic in comparison with the rigid IOL group but not significant at the 99% level of probability (Mann-Whitney U, p = 0.02). There was no significant difference in astigmatism between the groups.

CONCLUSIONS

Implanting a foldable acrylic IOL gave no post-operative benefit in visual acuity and contrast sensitivity to pseudophakes over a less expensive rigid PMMA IOL, within this post-operative period. This study did not provide a comparison between the two lenses regarding post-operative complications, in particular the important long-term complication of posterior capsular opacification (PCO). Until and if any particular advantage of a given IOL in reduced incidence of PCO is confirmed, it appears more economical to implant the conventional rigid PMMA IOL using small-incision surgery.

Atrial, B-type, and C-type natriuretic peptides cause mesenteric vasoconstriction in conscious dogs

Cardiovascular responses were compared with equimolar infusions of B-type (BNP) and C-type (CNP) with atrial natriuretic peptide (ANP) in conscious, instrumented dogs. On separate days, each natriuretic peptide or vehicle was infused (intravenously) at step-up doses of 2, 5, 10, and 20 pmol. kg-1. min-1 (20 min each dose) to increase circulating levels of the infused peptide from approximately 2- to 20-fold. Like ANP, infusions of BNP caused dose-related increases (P < 0.05) in mesenteric vascular resistance, urine flow, natriuresis, and hematocrit (changes at highest doses were 60 +/- 9, 334 +/- 113, 313 +/- 173, and 12 +/- 2%, respectively). BNP also lowered (P < 0. 05) plasma renin activity (-43 +/- 11%) and arterial pressure (-10 +/- 3%). Effects of BNP were independent of reflex sympathetic activation, since autonomic ganglion blockade did not attenuate the responses. CNP infusions had little effect except to increase (P < 0. 05) mesenteric vascular resistance (27 +/- 10%) and plasma ANP (41 +/- 7%). Cardiovascular actions of BNP, like those of ANP, counteract the renin-ANG system and may protect the heart by lowering cardiac preload (venous return) and afterload (arterial pressure) while maintaining blood flow to extrasplanchnic regions.

Screening for ophthalmic disease in older subjects using visual acuity and contrast sensitivity

OBJECTIVE

Despite early interest in contrast sensitivity as a screening test for ophthalmic disease, most published opinion suggests that there is no benefit over conventional measurement of visual acuity. Taking a primary care perspective of screening, the authors evaluated the ability to discriminate those with any diagnosed ophthalmic disease in a large sample representative of the general population.

DESIGN

Retrospective analysis of a clinical, cross-sectional survey. Snellen visual acuity, contrast sensitivity (Arden plates, American Optical contrast sensitivity test), and ophthalmic diagnosis were reported previously.

PARTICIPANTS

A sample of 3283 subjects, all aged at least 50 years, were selected randomly from residents of a health district in Sydney, Australia. Ophthalmologic diagnosis (ophthalmic disease presence/absence) had been confirmed for 2522 of these subjects.

MAIN OUTCOME MEASURES

Signal detection techniques (the receiver-operating characteristics function [ROC], quality ROC [QROC], and weighted kappa coefficient of association [kappa(r)]) were used to evaluate test discriminability.

RESULTS

Because analyses of right and left eyes were almost identical, only right eye results are presented. Advantages of kappa(r) over ROC were shown. Discrimination of those with diagnosed ophthalmic disease from those without ophthalmic disease was best with Arden plate 7 (kappa0.5 = 0.93) and was better than distance Snellen visual acuity (kappa0.5 = 0.59). Arden plate 7 (6.4 cyc/deg) correctly assigned 96% of subjects at its optimal pass-fail criterion.

CONCLUSIONS

In the primary care setting, a person older than 50 years of age with reduced contrast sensitivity, as determined by Arden plate 7, requires extra care in subsequent examinations because this person is likely to have an ophthalmic disease.

Vasoconstrictor actions of atrial natriuretic peptide in the splanchnic circulation of anesthetized dogs

Intravenous atrial natriuretic peptide (ANP) usually results in splanchnic vasoconstriction in humans or experimental animals that is accompanied by falls in blood pressure and/or cardiac output. To determine direct in vivo effects in the present study, ANP was infused (12 ng. kg-1. min-1) directly into the mesenteric (iMA) and hepatic (iHA) arterial beds of anesthetized dogs, thereby minimizing changes in blood pressure. Over the first 2 min of iMA infusion, rate of change in mesenteric vascular resistance was 19.6 +/- 5.4 mmHg. l-1. min-1/min, reaching a maximum increase in resistance of 22 +/- 4% compared with baseline after approximately 10 min. There was no evidence of vasodilatation at any stage. The mesenteric response was similar whether ANP was infused iMA, iHA, or via the femoral vein (30 ng. kg-1. min-1). In contrast, hepatic vasoconstrictor response to ANP infusion iHA or into the portal vein was only evident after approximately 5 min, reaching a maximum increase in hepatic vascular resistance of 11 +/- 6% after approximately 15 min iHA infusion. When preinfused through the gut vasculature (iMA), ANP increased hepatic vascular resistance earlier and reached similar levels (14 +/- 3%), despite a lower arterial concentration of ANP. It is proposed that a vasoconstrictor agent from the intestinal circulation contributed to ANP-induced splanchnic vasoconstriction.

Predicting the effects of optical defocus on human contrast sensitivity

We used diffraction modulation transfer functions and model eyes to predict the effect of defocus on the contrast sensitivity function (CSF) and compared these predictions with previously published experimental data. Using the principle that optically induced changes in the modulation transfer function should be paralleled by identical changes in the CSF, we used the modulation transfer function calculations with the best-focus CSF measurements to predict the defocused CSF. An aberration-free model predicted the effects of defocus well when the CSF was measured with small pupils (e.g., 2 mm) but not with larger pupils (6-8 mm). When the model included average aberrations, prediction of the defocused CSF with large pupils was better but remained inaccurate, failing, in particular, to reflect differences between individual subjects. Inclusion of measured aberrations for individual subjects provided accurate predictions in the shape of the monochromatic CSF of two of three subjects with hyperopic defocus and good predictions of the polychromatic CSF of two subjects with hyperopic defocus. Prediction of the effects of myopic defocus by use of measured individual aberrations of one subject were less successful. Hence a diffraction optics model can provide good predictions of the effects of defocus on the human CSF, given that one has knowledge of the individual ocular aberrations. These predictions are dependent on the quality of the aberration measurements.

ANP and bradycardic reflexes in hypertensive rats: influence of cardiac hypertrophy

In previous studies we demonstrated that in normotensive rats, but not in spontaneously hypertensive rats (SHR), atrial natriuretic peptide (ANP) enhances bradycardic reflexes through an action on cardiac vagal afferent pathways. The present study aimed to determine whether cardiac hypertrophy, hypertension, or a nonreversible genetic factor accounted for the insensitivity of SHR to ANP action on cardiac reflex pathways. SHR were treated with the angiotensin-converting enzyme (ACE) inhibitor perindopril (3 mg/kg per day) for 6 weeks from 4 to 9 weeks of age (SHR-S, n=10) or for 9 weeks from 4 to 12 weeks of age (SHR-L, n=10) or were untreated (SHR, n=10) to produce differential effects on blood pressure and left ventricle/body weight ratio (LV/BW). Untreated normotensive Wistar-Kyoto rats (WKY, n=10) were also studied. At 13 weeks of age, all rats were instrumented with aortic and jugular catheters, and at 14 weeks we measured heart rate reflexes to rapid intravenous infusions of methoxamine (100 microg/kg, cardiac baroreflex) and serotonin (5 to 60 microg/kg, von Bezold-Jarisch cardiac chemosensitive reflex), with either alpha-rat ANP (150 ng/kg per minute IV) or saline vehicle (270 microL/h IV) infusion. Perindopril treatment for 6-week (SHR-S) and 9-week (SHR-L) durations maintained blood pressure at normotensive levels in both groups. SHR-S exhibited a small degree of cardiac hypertrophy (LV/BW was 8% higher than in WKY but 11% less than in untreated SHR), but LV/BW was normalized in SHR-L (to within 1% of WKY LV/BW). In WKY, ANP significantly (P<0.05) enhanced bradycardic responses to both the cardiac baroreflex (by 42+/-10%) and von Bezold-Jarisch chemosensitive reflex (by 17+/-5%) activation but had no effect in SHR. The cardiac reflex action of ANP was restored in SHR-L (ANP enhanced reflex bradycardia by 28+/-12% and 36+/-8%, baroreflex and von Bezold-Jarisch reflex, respectively; P<0.05), but SHR-S, which developed some cardiac hypertrophy, remained unresponsive to ANP. Our results suggest that the inability of ANP to sensitize cardiac vagal (nonarterial) afferents in SHR was not due to an inherited irreversible component, or the hypertension per se, but was associated with the presence of cardiac hypertrophy. A functional consequence of hypertension-induced cardiac hypertrophy may be the inhibition of the cardioprotective action of ANP through cardiac vagal reflexes.

Subjective depth-of-focus of the eye

An experiment is described in which the subjective depth-of-focus (DOF) of the eye, defined as the range of focusing errors for which the image of the target appears to have the same clarity, contrast, and form as the optimal in-focus image, was measured as a function of the size of high contrast (99%) Snellen Es for 5 trained subjects under cycloplegia. Mean DOF increased by approximately 60% as the size of the letter detail increased from -0.2 to 0.87 log min arc (Snellen equivalent: 6/3.8 to 6/45), although there were considerable intersubject variations. DOF declined with increasing pupil diameter, the mean total DOFs being 0.86, 0.59, and 0.55 D for 2-, 4-, and 6-mm pupils, respectively. In a second experiment, use of low (21%) contrast letters with a 4-mm pupil and 4 subjects marginally increased the DOF (by 0.08 +/- 0.05 D); refraction also shifted in a myopic direction by a mean of 0.15 +/- 0.06 D compared with the high contrast letters. A third experiment with four less-experienced subjects demonstrated the importance of instruction and training in any measurement involving judgment of just-perceptible defocus blur. The clinical implications of the results for measurements of refraction and amplitude of accommodation are discussed.

ANP enhances bradycardic reflexes in normotensive but not spontaneously hypertensive rats

Baroreflex control of heart rate in spontaneously hypertensive rats (SHR) is defective, largely because of a poor vagal contribution to the reflex. We have demonstrated previously that atrial natriuretic peptide (ANP) enhances reflex bradycardia in normotensive rats through an action on nonarterial vagal afferent pathways. In the present study, we investigated whether ANP could reverse the baroreflex abnormality in SHR. Heart rate reflexes were activated by three different methods in conscious, instrumented SHR and Wistar-Kyoto rats (WKY) in the presence of intravenous infusions of vehicle (saline) or rat ANP (150 ng/kg per minute). Heart rate responses were measured by (1) the steady-state changes in blood pressure after alternating slow infusions (over approximately 15 to 30 seconds) of a pressor (methoxamine) and depressor (nitroprusside) drug (stimulating predominantly arterial baroreceptors), (2) the ramp method of rapid infusion of methoxamine (over < 10 seconds; stimulating arterial and cardiopulmonary baroreceptors), and (3) the von Bezold-Jarisch method of activating chemically sensitive cardiac receptors through serotonin injections. ANP enhanced the heart rate range of the arterial baroreflex (steady-state method) by 13 +/- 3% in WKY but had no significant effect on the sensitivity or any other parameter of the steady-state baroreflex. When a very rapid rise in blood pressure was elicited by the ramp method in WKY, ANP significantly enhanced baroreflex bradycardia (sensitivity increased by 29 +/- 9%, P < .05). ANP also enhanced the bradycardia of the von Bezold-Jarisch reflex (by 33 +/- 16%, P < .05) in WKY. By contrast, ANP did not influence baroreceptor or chemoreceptor heart rate reflex responses in SHR. We conclude that in normotensive rats, ANP facilitates cardiopulmonary bradycardic reflexes. The lack of effect of ANP in SHR may be related to an underlying structural or genetic alteration in their cardiac sensors, perhaps associated with cardiac hypertrophy, that prevents the ANP-induced activation of cardiac sensory afferents, resulting in cardioinhibition.

Consequences of monocular diplopia for the contrast sensitivity function

Though the human eye generally creates a single image on the retina, the literature contains many examples showing perceptual monocular diplopia. Previously, monocular diplopia resulting from astigmatic defocus has been demonstrated to cause a notch (local minimum) in the contrast sensitivity function (CSF). We examine Verhoeff's (1900) model which explains how monocular diplopia can occur through an interaction between defocus and common ocular aberrations. From the measured ocular transverse aberration function and from the measured monocular diplopia of three cyclopleged subjects we predicted multiple notches in the CSF with hyperopic spherical defocus. Monochromatic and polychromatic CSF were measured for vertical gratings with best refraction and with simulated myopia and hyperopia. Multiple notches in CSF were observed experimentally. Notches in the polychromatic CSF were smaller and broader than those found in the monochromatic CSF. Our aberration model was successful in predicting notches in the CSF with hyperopic spherical defocus. The implications for clinical measurement of CSF are discussed.

Monocular diplopia caused by ocular aberrations and hyperopic defocus

As a single aperture, approximately monofocal optical system, the human eye generally creates a single image on the retina. However, the literature contains many reports of perceptual monocular diplopia. While it is easy to understand how distortion may produce monocular diplopia, its reported high incidence in normal eyes is less easily understood. We examine a model which ascribes monocular diplopia to an interaction between defocus and ocular spherical aberration. Using a psychophysical hyperacuity-based alignment procedure we measured the transverse aberration function in 0.5 mm steps horizontally across the pupil in the eyes of three cyclopleged subjects. Ocular transverse aberration functions were derived with best refraction and with simulated myopia and hyperopia. Monocular diplopia was also measured under the same conditions. All three subjects showed significant, but different, degrees of positive spherical aberration. The measured ocular transverse aberration functions were predictably modified by the hyperopic and myopic defocus. Hyperopic defocus combined with positive (myopic) spherical aberration changes a monotonic transverse aberration function with a single inflection point into a biphasic function with two inflection points. The locations of the inflections predict the presence and magnitude of the perceived diplopia. These experimental results confirm Verhoeff's (1900) hypothesis for the ocular cause of monocular diplopia.

Spatial frequency dependent observer bias in the measurement of contrast sensitivity

A previously reported spatial frequency dependent change in contrast sensitivity, apparently produced by the psychometric method used, was investigated in two experiments. A relative reduction in the measured contrast sensitivity function at higher spatial frequencies was found when using a simple single staircase procedure, even when all external characteristics of the presentation procedure were the same as a more sophisticated and more reliable psychometric method (adaptive probit estimation). The estimated false-negative response rate was found to be greater for the single staircase procedure and was greater at a higher spatial frequency, while the false-positive response rate to interleaved blank presentations did not vary between spatial frequencies and between the two psychometric methods. This supports the suggestion that some subjects, given a knowledge of the psychometric method controlling grating contrast, may adopt different decision criteria at different spatial frequencies.

Evidence for a renomedullary vasodepressor hormone

1. Recent physiological experiments have established that increasing the perfusion pressure of the kidney causes the release of vasodepressor substance from the renal medulla. 2. The substance is not a platelet activating factor, a prostaglandin or nitric oxide and the vasodepressor response to increased renal perfusion is not due simply to inhibition of renin release. 3. The mechanisms by which the renomedullary vasodepressor substance lowers arterial pressure remain to be determined. Sympathoinhibition may account for part of the response, but the hypotension still occurs in autonomic ganglion blocked animals. 4. The source of substance appears to be the renomedullary interstitial cells, though the control of the production and release of the substance remain to be determined. 5. The substance may be a lipid but it is yet to be fully isolated and identified. 6. The threshold for release of the substance appears to be close to normal resting arterial blood pressure. 7. Despite strong evidence that the renal medulla releases a vasodepressor hormone in response to increased renal perfusion pressure, much is still to be determined regarding the physiology of this hormone and its involvement in the aetiology of hypertension.

Alveolar epithelial lining fluid cellularity, protein and endothelin-1 in children with congenital heart disease

This study applied bronchoalveolar lavage (BAL) to children with congenital heart disease (CHD) prior to elective cardiac catheterization (n = 48), to determine the influence of pulmonary blood flow and viral infection on the alveolar epithelial lining fluid (ELF) concentration of leucocytes, protein and endothelin-1 (ET-1). Lower respiratory tract (LRT) viral infection was defined as either a positive immunofluorescence for virus, or a virus cultured from the bronchoalveolar lavage fluid (BALF). Haemodynamic status was determined at cardiac catheterization. Normative data for BALF, but not ELF parameters, were obtained from 26 asymptomatic, noninfected normal children undergoing elective surgery. In the absence of LRT infection, the BALF macrophage, lymphocyte and neutrophil differential in CHD was not significantly different from the normal controls. In CHD, both increased pulmonary-to-systemic flow ratio (Q'p/Q's) and increased pulmonary artery-to-left ventricular pressure ratio PAP/LVP were associated with a decrease in ELF protein (rs = -0.59; p < 0.0001; and rs = -0.50; p < 0.0001 respectively). A respiratory virus was isolated from the BALF in 8 (17%) of CHD children. Virus isolation was associated with an increased ELF total protein (p < 0.05 vs no infection), a decreased alveolar macrophage differential count (p < 0.01), and an increased neutrophil differential count (p < 0.05). ET-1 was detected in the BALF of 83% of the noninfected CHD children compared to only 23% of the controls (p < 0.001). ELF ET-1 concentrations did not correlate with haemodynamic status in CHD, but were up to 100 times higher than paired plasma levels. We conclude that, in congenital heart disease, both lower respiratory tract viral infection and increased pulmonary blood flow and/or pulmonary vascular pressure influence the alveolar milieu. High alveolar epithelial lining fluid concentrations of endothelin-1 occur in congenital heart disease, but the stimulus for pulmonary endothelin-1 production is unclear.

Long-term follow-up of a randomised trial of combined chemoradiotherapy induction treatment, with and without maintenance chemotherapy in patients with small cell carcinoma of the lung

The toxicity and efficacy of concomitant chemotherapy and radiotherapy as induction therapy was evaluated in patients with previously untreated small cell carcinoma of the lung (SCLC), and in responding patients the value of maintenance chemotherapy was examined. 202 patients received induction chemotherapy with cisplatin and etoposide (EP), in combination with cranial and local radiotherapy. 85 patients (42%) developed grades III and IV myelosuppression, the main toxicity of induction treatment. Of the 154 responding patients, 129 were randomised to maintenance chemotherapy with vincristine, doxorubicin and cyclophosphamide (VAC) or no further treatment. The response rate for the limited disease patients (LD) was 87%, 62% achieving a complete response (CR) and the response rate for extensive disease patients (ED) was 68%, with 26% achieving a CR. 17 patients (11%) completed 10 courses of maintenance chemotherapy. 32 patients (57%) developed grade III and IV neutropenia. Median survival for all patients was 53 weeks (LD, 70 weeks; ED, 42.5 weeks). There was no significant difference in overall survival (OS) or disease-free survival (DFS) in the two randomisation arms. This study shows that EP combined with radiotherapy is an effective induction regimen in SCLC. Maintenance chemotherapy with VAC is not associated with increased survival but has significant toxicity after such induction treatment.

Increasing resting vascular tone in conscious dogs does not alter the mesenteric vasoconstrictor responses to ANP

1. There is considerable in vitro evidence that, at high concentrations, atrial natriuretic peptide (ANP) acts directly on pre-constricted blood vessels to cause vasorelaxation. Previously, we have seen vasoconstriction rather than vasodilatation in conscious dogs at physiological levels of the peptide. It is possible that the low resting vascular tone in our conscious, unstressed animals prevented the manifestation of the relaxant properties of ANP in vivo. 2. In the present study in conscious, instrumented dogs, we studied the mesenteric vascular responses to 10 min infusions of ANP (10, 25, 50 and 100 ng/kg per min, i.v.) when resting vascular tone was enhanced with a continuous infusion of AVP (75 pg/kg per min, i.v.) and compared these with responses in the normal condition (no added AVP). 3. Mesenteric vascular resistance was increased by ANP (10, 25, 50 and 100 ng/kg per min) by 9 +/- 2, 20 +/- 6, 29 +/- 7 and 32 +/- 9%, respectively. Increased resting vascular tone did not alter the mesenteric vasoconstrictor response to ANP. Thus, the discrepancy between in vitro (vasorelaxation) and in vivo (vasoconstriction) findings may be the result of the widely different concentrations of ANP used, rather than the state of resting vascular tone.