Clinical reporting of radiographs by radiographers: Policy and practice guidance for regional imaging networks

OBJECTIVES

Radiographer reporting is an essential component of imaging across the United Kingdom. Since the previous policy and practice guidance in 2004 the role and contribution of reporting radiographers has changed significantly. The move to imaging networks further reinforces the need for consistency in scope of practice and clinical governance for radiographer reporting.

KEY FINDINGS

This guidance provides a consistent, evidence-based template for planning a reporting service, resourcing, clinical governance, preceptorship, volume and frequency of reporting, a peer learning framework and expected standards.

CONCLUSION

Developed for North Central and East London, this framework and standards will help reduce unwarranted variation.

IMPLICATIONS FOR PRACTICE

Consistency in practice could help maximise the contribution of radiographer reporting.

Liraglutide use and evaluation of pancreatic outcomes in a US commercially insured population

AIMS

Both acute pancreatitis (AP) and pancreatic cancer (PC) have been areas of focus for studies of incretin drugs. This 5-year prospective cohort study aimed to quantify possible associations between liraglutide and risk of AP and PC as compared to other antidiabetic drugs (ADs).

MATERIALS AND METHODS

Patients initiating liraglutide or other ADs who were enrolled in a US health plan (2010-2014) were included. Comparisons of AP and PC incidence rates were made between matched cohorts of liraglutide initiators and initiators of other ADs. Adjudicated AP cases and algorithm-based PC cases were identified. Propensity score-matched intention-to-treat (ITT) and time-on-drug (TOD) analyses were completed using Poisson regression. A latency analysis was performed for PC.

RESULTS

Median follow-up was 405 days for AP cohorts (9995 liraglutide, 1:1 matched to all comparators) and 503 days for PC cohorts (35 163 liraglutide, 1:1 matched to all comparators). In the primary AP analysis, "current" use of liraglutide was not significantly associated with elevated risk across comparators (all comparators relative risk [RR] = 1.2; 95% confidence interval [CI], 0.6-2.3). ITT results were similar where, in the primary analysis, no RRs were significantly associated with PC (all comparators RR = 0.7; 95% CI, 0.3-1.4); latency and TOD analyses did not alter findings. There was no evidence of a dose-response effect.

CONCLUSIONS

Liraglutide was not associated with an increased risk of AP or PC, although risk estimates were more variable for AP, and numbers of cases for both outcomes were limited because of the rarity of outcomes.

Is there an association between liraglutide use and female breast cancer in a real-world setting?

BACKGROUND

Liraglutide is a human glucagon-like peptide-1 receptor agonist approved for treatment of adults with type 2 diabetes mellitus at a maximum dose of 1.8 mg/day (Victoza^®) and more recently at 3.0 mg/day for weight management (Saxenda^®). During the evaluation of liraglutide for approval in weight management, a minor imbalance in the numbers of reported breast neoplasms was observed, motivating the present study. Our objective was to quantify the association between liraglutide and incidence of breast cancer (BC) among women in a real-world setting.

PATIENTS AND METHODS

Women initiating liraglutide or other antidiabetic therapies and who were enrolled in a large US health plan (2010-2014) were included. Comparisons of BC incidence rates were made between matched cohorts of initiators of liraglutide and cohorts of initiators of exenatide, metformin, pioglitazone, sulfonylureas, and dipeptidyl peptidase-4 inhibitors separately and as two "all comparators" groupings: with or without exenatide. Women with two or more claims with BC diagnosis codes within 61days of each other were identified as possible cases, with additional confirmation by clinician review of comprehensive claims listings. Propensity score matched intention-to-treat (ITT) and time-on-drug (TOD) analyses were completed via Poisson regression. A latency analysis was performed.

RESULTS

Relative risks for BC for liraglutide vs comparators from the ITT analyses ranged from 0.90 (95% CI: 0.67-1.22) for both the "all comparator" and "all comparator except exenatide" cohorts to 1.46 (95% CI: 0.96-2.22) relative to exenatide. Latency analyses excluding the first year of follow-up yielded slightly attenuated point estimates. The TOD analyses of cumulative use of liraglutide suggested no increased risk of BC.

CONCLUSION

Neither the ITT (overall or latency analysis) nor cumulative TOD analyses suggested an elevated risk of BC among liraglutide initiators. Short length of follow-up and the potential for confounding by unmeasured factors limit the full assessment of long-term risk.

Interaction of thrombospondin1 and CD36 contributes to obesity-associated podocytopathy

Obesity is associated with podocyte injury and the development of proteinuria. Elevated plasma free fatty acid is one of the characteristics of obesity and has been linked to podocyte dysfunction. However, the mechanisms remain unclear. In the current study, we examined the effect of saturated free fatty acid (FFA) on human podocyte apoptosis and function in vitro. The mechanism and its in vivo relevance were also determined. We found that FFA treatment induced human podocyte apoptosis and dysfunction, which was associated with increased expression of a matricellular protein-thrombospondin1 (TSP1). FFA stimulated TSP1 expression in podocytes at the transcriptional levels through activation of MAPK pathway. Addition of purified TSP1 to cell culture media induced podocyte apoptosis and dysfunction. Tis effect is though a TGF-β independent mechanism. Moreover, peptide treatment to block TSP1 binding to its receptor-CD36 attenuated FFA induced podocyte apoptosis, suggesting that TSP1/CD36 interaction mediates FFA-induced podocyte apoptosis. Importantly, using a diet-induced obese mouse model, in vivo data demonstrated that obesity-associated podocyte apoptosis and dysfunction were attenuated in TSP1 deficient mice as well as in CD36 deficient mice. Taken together, these studies provide novel evidence that the interaction of TSP1 with its receptor CD36 contributes to obesity--associated podocytopathy.

Thrombospondin1 deficiency attenuates obesity-associated microvascular complications in ApoE-/- mice

Obesity is associated with insulin resistance and the increased development of vascular complications. Previously, we have demonstrated that thrombospondin1 (TSP1) regulates macrophage function and contributes to obesity associated inflammation and insulin resistance. However, the role of TSP1 in the development of obesity associated vascular complications is not clear. Therefore, in the current study, we investigated whether TSP1 deficiency protects mice from obesity associated micro as well as macro-vascular complications in ApoE-/- mice. In this study, male ApoE-/- mice and ApoE-/-TSP1-/- mice were fed with a low-fat (LF) or a high-fat (HF) diet for 16 weeks. We found that body weight and fat mass increased similarly between the ApoE-/-TSP1-/- mice and ApoE-/- mice under HF feeding conditions. However, as compared to obese ApoE-/- mice, obese ApoE-/-TSP1-/- mice had improved glucose tolerance, increased insulin sensitivity, and reduced systemic inflammation. Aortic atherosclerotic lesion formation was similar in these two groups of mice. In contrast, albuminuria was attenuated and kidney fibrosis was reduced in obese ApoE-/-TSP1-/- mice compared to obese ApoE-/- mice. The improved kidney function in obese ApoE-/-TSP1-/- mice was associated with decreased renal lipid accumulation. Together, these data suggest that TSP1 deficiency did not affect the development of obesity associated macro-vascular complication, but attenuated obesity associated micro-vascular complications.

CD47 deficiency protects mice from diet-induced obesity and improves whole body glucose tolerance and insulin sensitivity

CD47 is a transmembrane protein with several functions including self-recognition, immune cell communication, and cell signaling. Although it has been extensively studied in cancer and ischemia, CD47 function in obesity has never been explored. In this study, we utilized CD47 deficient mice in a high-fat diet induced obesity model to study for the first time whether CD47 plays a role in the development of obesity and metabolic complications. Male CD47 deficient and wild type (WT) control mice were fed with either low fat (LF) or high fat (HF) diets for 16 weeks. Interestingly, we found that CD47 deficient mice were protected from HF diet-induced obesity displaying decreased weight gain and reduced adiposity. This led to decreased MCP1/CCR2 dependent macrophage infiltration into adipose tissue and reduced inflammation, resulting in improved glucose tolerance and insulin sensitivity. In addition, CD47 deficiency stimulated the expression of UCP1 and carnitine palmitoyltransferase 1b (CPT1b) levels in brown adipose tissue, leading to increased lipid utilization and heat production. This contributes to the increased energy utilization and reduced adiposity observed in these mice. Taken together, these data revealed a novel role for CD47 in the development of obesity and its related metabolic complications.

A cross-sectional study of the identification of prevalent asthma and chronic obstructive pulmonary disease among initiators of long-acting β-agonists in health insurance claims data

BACKGROUND

Claims data are potentially useful for identifying long-acting β-agonist (LABA) use by patients with asthma, a practice that is associated with increased mortality. We evaluated the accuracy of claims data for classifying prevalent asthma and chronic obstructive pulmonary disease (COPD) among initiators of LABAs.

METHODS

This study included adult LABA initiators during 2005-2008 in a US commercial health plan. Diagnosis codes from the 6 months before LABA initiation identified potential asthma or COPD and a physician adjudicated case status using abstracted medical records. We estimated the positive predictive value (PPV) and 95% confidence intervals (CI) of covariate patterns for identifying asthma and COPD.

RESULTS

We sought 520 medical records at random from 225,079 LABA initiators and received 370 (71%). The PPV for at least one asthma claim was 74% (CI 63-82), and decreased as age increased. Having at least one COPD claim resulted in a PPV of 82% (CI 72-89), and of over 90% among older patients, men, and recipients of inhaled anticholinergic drugs. Only 2% (CI 0.2-7.6) of patients with a claim for COPD alone were found to have both COPD and asthma, while 9% (CI 4-16) had asthma only. Twenty-one percent (CI 14-30) of patients with claims for both diagnoses had both conditions. Among patients with no asthma or COPD claims, 62% (CI 50-72) had no confirmed diagnosis and 29% (CI 19-39) had confirmed asthma.

CONCLUSIONS

Subsets of patients with asthma, COPD, and both conditions can be identified and differentiated using claims data, although categorization of the remaining patients is infeasible. Safety surveillance for off-label use of LABAs must account for this limitation.

Increasing cGMP-dependent protein kinase activity attenuates unilateral ureteral obstruction-induced renal fibrosis

Our previous studies support the protective effect of cGMP and cGMP-dependent protein kinase I (PKG-I) pathway on the development of renal fibrosis. Therefore, in the present studies, we determined whether pharmacologically or genetically increased PKG activity attenuates renal fibrosis in a unilateral ureteral obstruction (UUO) model and also examined the mechanisms involved. To increase PKG activity, we used the phosphodiesterase 5 inhibitor sildenafil and PKG transgenic mice. UUO model was induced in wild-type or PKG-I transgenic mice by ligating the left lateral ureteral and the renal fibrosis was observed after 14 days of ligation. Sildenafil was administered into wild-type UUO mice for 14 days. In vitro, macrophage and proximal tubular cell function was also analyzed. We found that sildenafil treatment or PKG transgenic mice had significantly reduced UUO-induced renal fibrosis, which was associated with reduced TGF-β signaling and reduced macrophage infiltration into kidney interstitial. In vitro data further demonstrated that both macrophages and proximal tubular cells were important sources of UUO-induced renal TGF-β levels. The interaction between macrophages and tubular cells contributes to TGF-β-induced renal fibrosis. Taken together, these data suggest that increasing PKG activity ameliorates renal fibrosis in part through regulation of macrophage and tubular cell function, leading to reduced TGF-β-induced fibrosis.

Thrombospondin 1 mediates renal dysfunction in a mouse model of high-fat diet-induced obesity

Obesity is prevalent worldwide and is a major risk factor for many diseases including renal complications. Thrombospondin 1 (TSP1), a multifunctional extracellular matrix protein, plays an important role in diabetic kidney diseases. However, whether TSP1 plays a role in obesity-related kidney disease is unknown. In the present studies, the role of TSP1 in obesity-induced renal dysfunction was determined by using a diet-induced obese mouse model. The results demonstrated that TSP1 was significantly upregulated in the kidney from obese mice. The increased TSP1 was localized in the glomerular mesangium as well as in the tubular system from obese wild-type mice. Obese wild-type mice developed renal hypertrophy and albuminuria, which was associated with increased kidney macrophage infiltration, augmented kidney inflammation, and activated transforming growth factor (TGF)-β signaling and renal fibrosis. In contrast, obese TSP1-deficient mice did not develop these kidney damages. Furthermore, in vitro studies demonstrated that leptin treatment stimulated the expression of TSP1, TGF-β1, fibronectin, and collagen type IV in mesangial cells isolated from wild-type mice. These leptin-stimulated effects were abolished in TSP1-deficient mesangial cells. Taken together, these data suggest that TSP1 is an important mediator for obesity- or hyperleptinemia-induced kidney dysfunction.

Increasing cGMP-dependent protein kinase I activity attenuates cisplatin-induced kidney injury through protection of mitochondria function

Cisplatin is widely used to treat malignancies. However, its major limitation is the development of dose-dependent nephrotoxicity. The precise mechanisms of cisplatin-induced kidney damage remain unclear, and the renoprotective agents during cisplatin treatment are still lacking. Here, we demonstrated that the expression and activity of cGMP-dependent protein kinase-I (PKG-I) were reduced in cisplatin-treated renal tubular cells in vitro as well as in the kidney tissues from cisplatin-treated mice in vivo. Increasing PKG activity by both pharmacological and genetic approaches attenuated cisplatin-induced kidney cell apoptosis in vitro. This was accompanied by decreased Bax/Bcl2 ratio, caspase 3 activity, and cytochrome c release. Cisplatin-induced mitochondria membrane potential loss in the tubular cells was also prevented by increased PKG activity. All of these data suggest a protective effect of PKG on mitochondria function in renal tubular cells. Importantly, increasing PKG activity pharmacologically or genetically diminished cisplatin-induced tubular damage and preserved renal function during cisplatin treatment in vivo. Mitochondria structural and functional damage in the kidney from cisplatin-treated mice was inhibited by increased PKG activity. In addition, increasing PKG activity enhanced ciaplatin-induced cell death in several cancer cell lines. Taken together, these results suggest that increasing PKG activity may be a novel option for renoprotection during cisplatin-based chemotherapy.

Biliary dyskinesia: how effective is cholecystectomy?

INTRODUCTION

Studies on biliary dyskinesia have been based on short-term surgical follow-up and do not take into consideration that most patients are discharged from surgical follow-up after the first postoperative visit and that for persistent or recurrent symptoms they are frequently seen by primary care providers and subsequently referred to gastroenterologists. We aimed to study this pattern and assess which factors predict patients that will benefit from cholecystectomy.

METHOD

This is a retrospective analysis of medical records of patients who underwent cholecystectomy for biliary dyskinesia from February 2001 to January 2010 with a minimum postoperative follow-up of 6 months.

RESULTS

At initial surgical follow-up, 19 of 141 (13.4%) patients said they had persistent symptoms. However, when subsequent visits were analyzed, 61 of 141 (43.3%) patients with persistent or recurrent symptoms saw their primary care provider. These symptoms were epigastric or right upper quadrant pain in 43 patients or 30% of those undergoing cholecystectomy. The only factor that distinguished patients with and without resolution of symptoms after cholecystectomy was the pathologic finding of inflammation (p = 0.02).

CONCLUSION

Cholecystectomy does not appear to be as effective for biliary dyskinesia when long-term follow-up is evaluated.

Adherence to recommended dosing and monitoring for mitoxantrone in patients with multiple sclerosis: a healthcare claims database study supplemented with medical records--the RETRO study

PURPOSE

Mitoxantrone was approved for treatment of multiple sclerosis (MS) in October 2000. Monitoring and dosing guidelines in the product labeling accompanying this indication include blood counts, liver function, and pregnancy tests at each administration. Due to potential cardiotoxicity, left ventricular ejection fraction (LVEF) testing prior to initial infusion and all infusions at a cumulative dose >or=100 mg/m(2) was recommended until April 2005 when LVEF testing before all infusions was recommended in the approved labeling. We sought to estimate provider adherence to dosing and monitoring guidelines and the effect of changes in LVEF monitoring guidelines.

METHODS

MS patients who received mitoxantrone between October 2000 and June 2006 were selected from the claims of a large US health insurer. Claims for infusions and for specified tests prior to an infusion determined adherence to guidelines, with medical records providing additional information for a subset.

RESULTS

There were 1827 mitoxantrone infusions to 548 eligible patients; medical records were obtained for 261 patients (1096 infusions). Most mitoxantrone recipients were 30-59 years of age and 73% were female. Adherence to recommended dosing was higher than for recommended monitoring. Blood counts were conducted for most infusions (78-83%), while liver function tests (LFT) were performed less often (47-54% of infusions). Pregnancy tests were performed for 10% or fewer of the infusions administered to reproductive age women. Adherence with LVEF testing guidelines improved following labeling changes.

CONCLUSIONS

Adherence to recommended monitoring was incomplete, but amenable to change. Automated assessment through insurance claims supplemented with medical record data provides a balanced means for studying adherence to recommendations.

Venous Thromboembolism, Myocardial Infarction, and Stroke Among Transdermal Contraceptive System Users

OBJECTIVE

To estimate the incidence of venous thromboembolism, acute myocardial infarction, and ischemic stroke among transdermal contraceptive system users compared with users of norgestimate-containing oral contraceptives with 35 mcg ethinyl estradiol.

METHODS

We began with insurance claims data from UnitedHealthcare. We identified women exposed to the transdermal contraceptive system or norgestimate-containing oral contraceptives from April 2002 through December 2004. Outcomes were confirmed from medical records. We calculated incidence rates and age-adjusted incidence rate ratios. In a nested case-control analysis, we investigated and controlled for confounding.

RESULTS

There were 49,048 woman-years of transdermal contraceptive system exposure and 202,344 woman-years of norgestimate-containing oral contraceptives exposure. There was a more than two-fold increase in the venous thromboembolism rate (incidence rate ratio 2.2, 95% confidence interval [CI] 1.3-3.8) among transdermal contraceptive system users (20 cases, 40.8 per 100,000 woman-years) compared with norgestimate-containing oral contraceptives users (37 cases, 18.3 per 100,000 woman-years). Acute myocardial infarction occurred in three transdermal contraceptive system users compared with seven among norgestimate-containing oral contraceptives users (incidence rate ratio 1.8, 95% CI 0.5-6.8). No strokes occurred among transdermal contraceptive system users, whereas 10 occurred among norgestimate-containing oral contraceptives users. In the nested case-control analysis, after exclusions for high-risk factors, the odds ratio for venous thromboembolism was 2.4 (95% CI 1.1-5.5).

CONCLUSION

There was a more than two-fold increase in the risk of venous thromboembolism associated with use of the transdermal contraceptive system. Acute myocardial infarction and stroke occurred too rarely to ascertain precise risk estimates.

LEVEL OF EVIDENCE

II.

A porcine model of acute quadriplegic myopathy: a feasibility study

BACKGROUND

The mechanisms underlying acute quadriplegic myopathy (AQM) are poorly understood, partly as a result of the fact that patients are generally diagnosed at a late stage of the disease. Accordingly, there is a need for relevant experimental animal models aimed at identifying underlying mechanisms.

METHODS

Pigs were mechanically ventilated and exposed to various combinations of agents, i.e. pharmacological neuromuscular blockade, corticosteroids and/or sepsis, for a period of 5 days. Electromyography and myofibrillar protein and mRNA expression were analysed using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), confocal microscopy, histochemistry and real-time polymerase chain reaction (PCR).

RESULTS

A decreased compound muscle action potential, normal motor nerve conduction velocities, and intact sensory nerve function were observed. Messenger RNA expression, determined by real-time PCR, of the myofibrillar proteins myosin and actin decreased in spinal and cranial nerve innervated muscles, suggesting that the loss of myosin observed in AQM patients is not solely the result of myofibrillar protein degradation.

CONCLUSION

The present porcine AQM model demonstrated findings largely in accordance with results previously reported in patients and offers a feasible approach to future mechanistic studies aimed at identifying underlying mechanisms and developing improved diagnostic tests and intervention strategies.

Drug Copayment and Adherence in Chronic Heart Failure: Effect on Cost and Outcomes

STUDY OBJECTIVE

To measure the association among prescription copayment, drug adherence, and subsequent health outcomes among patients with chronic heart failure (CHF).

DESIGN

Retrospective cohort study.

DATA SOURCE

Database of a large, national health insurance plan.

PATIENTS

Patients with CHF receiving commercial and Medicare supplemental benefits.

MEASUREMENTS AND MAIN RESULTS

We estimated adherence to therapy with beta-blockers or angiotensin-converting enzyme (ACE) inhibitors in 2002 by using the medication possession ratio, an estimate of the proportion of days a patient was exposed to a drug while taking a drug regimen. For 2003, we measured the annualized total cost of health care and identified hospitalizations with a diagnostic code for CHF. We used a two-stage regression approach to model the association among copayment, adherence, and patient outcomes. For patients taking ACE inhibitors, a $10 increase in copayment was associated with a 2.6% decrease in the medication possession ratio (95% confidence interval [CI] 2.0-3.1%). This change in adherence was associated with a predicted 0.8% decrease in medical costs (95% CI -4.2-2.5%) but a predicted 6.1% increase in the risk of hospitalization for CHF (95% CI 0.5-12.0%). Among patients taking beta-blockers, a $10 increase in copayment was associated with a 1.8% decrease in the medication possession ratio (95% CI 1.4-2.2%). This change in adherence was associated with a predicted 2.8% decrease in medical costs (95% CI -5.9-0.1%) and a predicted 8.7% increase in the risk of hospitalization for CHF (95% CI 3.8-13.8%).

CONCLUSION

Among patients with CHF, higher drug copayments were associated with poorer adherence. The change was relatively small and did not affect predicted total health care costs, but it was sufficient to increase the predicted risk of hospitalization for CHF.

Impact of post-synaptic block of neuromuscular transmission, muscle unloading and mechanical ventilation on skeletal muscle protein and mRNA expression

To analyse mechanisms of muscle wasting in intensive care unit patients, we developed an experimental model where rats were pharmacologically paralysed by post-synaptic block of neuromuscular transmission (NMB) and mechanically ventilated for 9+/-2 days. Specific interest was focused on the effects on protein and mRNA expression of sarcomeric proteins, i.e., myosin heavy chain (MyHC), actin, myosin-binding protein C (MyBP-C) and myosin-binding protein H (MyBP-H) in fast- and slow-twitch limb, respiratory and masticatory muscles. Muscle-specific differences were observed in response to NMB at both the protein and mRNA levels. At the protein level, a decreased MyHC-to-actin ratio was observed in all muscles excluding the diaphragm, whereas at the mRNA level a decreased expression of the dominating MyHC isoform(s) was observed in the hind limb and intercostal muscles, but not in the diaphragm and masseter muscles. MyBP-C mRNA expression was decreased in the limb muscles, but it otherwise remained unaffected. MyBP-H conversely increased in all muscles. Furthermore, we found myofibrillar protein and mRNA expression to be affected differently when comparing NMB animals with peripherally denervated (DEN) ambulatory rats. We report that NMB has both a larger and different impact on muscle, at the protein and mRNA levels, than DEN has.

Role of gammaENaC subunit in lung liquid clearance and electrolyte balance in newborn mice. Insights into perinatal adaptation and pseudohypoaldosteronism

Genetic evidence supports a critical role for the epithelial sodium channel (ENaC) in both clearance of fetal lung liquid at birth and total body electrolyte homeostasis. Evidence from heterologous expression systems suggests that expression of the alphaENaC subunit is essential for channel function, whereas residual channel function can be measured in the absence of beta or gamma subunits. We generated mice without gammaENaC (gammaENaC -/-) to test the role of this subunit in neonatal lung liquid clearance and total body electrolyte balance. Relative to controls, gammaENaC (-/-) pups showed low urinary [K+] and high urinary [Na+] and died between 24 and 36 h, probably from hyperkalemia (gammaENaC -/- 18.3 mEq/l, control littermates 9.7 mEq/l). Newborn gammaENaC (-/-) mice cleared lung liquid more slowly than control littermates, but lung water at 12 h (wet/dry = 5.5) was nearly normal (wet/dry = 5.3). This study suggests that gammaENaC facilitates neonatal lung liquid clearance and is critical for renal Na+ and K+ transport, and that low level Na+ transport may be sufficient for perinatal lung liquid absorption but insufficient to maintain electrolyte balance by the distal nephron. The gammaENaC (-/-) newborn exhibits a phenotype that resembles the clinical manifestations of human neonatal PHA1.

Binocular rivalry and motion perception

In a series of experiments psychophysical techniques were used to study the relation between binocular rivalry and motion perception. An initial series of experiments confirmed that motion enhances the predominance of an eye during rivalry, although the direction of motion does not matter. The presence of an annulus of motion immediately surrounding one eye's rival target greatly enhances dominance of that target, but the influence of the annulus progressively decreases as the separation between disk and annulus increased. Opponent directions of motion in disk and annulus yield greater dominance than when dots in the disk and annulus moved in identical directions. In a second experiment that two eyes were adapted to orthogonal directions of motion, generating strong, distinctively different monocular motion aftereffects (MAEs). Even though the two eyes view physically identical random-motion displays following differential adaptation, binocular rivalry of the discrepant MAEs can occur. Finally, using a stimulus replacement technique to measure detectability of translational and rotational motion, it was found that both types of motion were readily detected during periods of dominance but went undetected during periods of suppression. Taken together, these results bear on the process responsible for rivalry and its neural locus relative to the analysis of different types of motion.

Critical weight at menarche. Critique of a hypothesis

The critical weight hypothesis in relation to menarche, which is known as the Frisch-Revelle model, has been examined. Since, in eight samples, girls reached menarche at weights spanning a 71.4-kg (157-lb) range, Frisch and Revelle's concept of a critical weight of 47 to 48 kg (104 to 106 lb) cannot be applied meaningfully to individuals. Neither can the suggestion of an invariant mean weight be accepted, because significant differences occur among the mean menarcheal weights for several samples of normal white girls. Finally, when stature is held constant, there is some evidence that girls who reach menarche at younger ages are heavier than those who begin menstruating at older ages. Apparent reductions in variability when the estimated amount of total body water is used instead of body weight may result from statistical artifacts associated with regression analysis.