Optimizing and simplifying post-traumatic amnesia testing after moderate-severe traumatic brain injury despite common confounders in routine practice.

The duration of post-traumatic amnesia (PTA) following traumatic brain injury (TBI) is a key diagnostic and outcome indicator. However, concerningly, different PTA paradigms record different PTA durations: some over-estimate, others under-estimate, PTA. Thus, a compromise is implied. The potential effect of in-hospital confounders including opioids is unknown. Three clinical groups were prospectively recruited. Group-1: in-patients with moderate-severe-TBI (MS-TBI), considered likely 'in-PTA'. Group-2: patients rehabilitating after recent MS-TBI, considered 'out-of-PTA'. Group-3: orthopaedic in-patients without TBI undergoing elective surgery. Only Groups 1&3 were taking opioids. All were administered the Westmead Post-traumatic Amnesia Scale (WPTAS) and the Galveston Orientation and Amnesia Test (GOAT). Results were obtained in n = 56 (Group-1:n = 18, Group-2:n = 13 and Group-3:n = 25). On WPTAS, Groups 1&3 scored similarly, but significantly lower than, Group-2 (χ2 = 8.2, P = 0.017). Contrariwise, on GOAT, Group-1 scored significantly lower than Groups 2&3 (χ2 = 23.99, P < 0.001): however, no patient scored GOAT <75. WPTAS showed moderate sensitivity (72%) but poor specificity (40%) in distinguishing Group-1 from Groups 2&3. Contrariwise, GOAT showed 100% specificity but 0% sensitivity. WPTAS 'day of week' and 'pictures' combined with GOAT 'transport medium to hospital', 'anterograde amnesia' and 'retrograde amnesia' maximized sensitivity (100%), specificity (85-88%), PPV (77-83%) and NPV (100%) in distinguishing Group-1 from Groups 2&3. CONCLUSIONS: Confounders including opioids likely affected WPTAS overall, but not GOAT specificity. A merger, whereby WPTAS sensitivity augmented GOAT specificity, was therefore sought. Favourable items from WPTAS (4/12) and GOAT (3/10) together optimized, and yet simplified, PTA testing; despite prevalent clinical confounders. Less, not more, 'PTA' items would benefit both patients and staff alike.

Ultrasound tissue characterisation of the superficial digital flexor tendons in juvenile Thoroughbred racehorses during early race training.

BACKGROUND: Injuries to the superficial digital flexor tendon (SDFT) are one of the leading causes of Thoroughbred (TB) wastage. Increasingly, the aim is to prevent injury rather than treat it. Conventional ultrasonography is not sufficiently sensitive to accurately monitor tendon and predict injury. Ultrasound tissue characterisation (UTC) is a relatively new technique, which improves tendon characterisation by providing a 3-dimensional (3D) SDFT reconstruction and objective calculation of fibre alignment by classifying fibres into one of 4 echo-types. OBJECTIVES: To report a reference range of echo-types in a population of normal juvenile TB racehorses. It was hypothesised that: UTC would be easy to use on juvenile TB racehorses in a field setting; that results would be repeatable; that the UTC would demonstrate a physiologic response of the tendon and, finally, that the technique would allow monitoring of the SDFT for early detection of degenerative changes. STUDY DESIGN: Prospective longitudinal cohort pilot study. METHODS: Thirty-two TB yearling racehorses were recruited. UTC measurements of bilateral forelimb SDFTs were taken every 60-90 days. The proportion of 4 echo-types were quantified as a relative percentage at specific zones over the length of the SDFT. Relationships were assessed by paired T tests or Wilcoxon signed rank tests. RESULTS: Mean percentage for echo-type I fibres were >85%; echo-type II fibres were <15%, with negligible echo-type III and IV. Significant right to left limb, zonal, and temporal differences in echo-type were identified. MAIN LIMITATIONS: No control group of untrained horses, limiting ability to differentiate whether findings were training-related as opposed to age-related changes. CONCLUSIONS: Changes in SDFT characterisation over the first 6 months of training were identified. UTC may provide useful objective information when assessing juvenile SDFTs. The Summary is available in Spanish - see Supporting Information.

Evaluation of videoendoscopic examinations of arytenoid function in the 2-year-old Thoroughbred: Can we all agree?

BACKGROUND: Upper respiratory tract (URT) endoscopic examination is a routine part of prepurchase examinations. Discrepancies have been documented in the assessment of arytenoid function grades (AFG) between veterinarians. OBJECTIVES: To document intra- and interobserver agreement for a population of multi-experience level veterinarians for assessment of AFG of 2-year-old Thoroughbreds. STUDY DESIGN: Observational cohort study. METHODS: One-hundred and fourteen URT videoendoscopic examinations were evaluated by 10 veterinarians. Veterinarians were categorised based on experience, into five groups, each group with two veterinarians. Arytenoid function was graded using the Havemeyer ordinal scale and then reclassified by the authors dichotomously into 'meets conditions of sale' (MCS) or 'does not meet conditions of sale'(DNMCS). Interobserver agreement of arytenoid function was assessed across all 10 veterinarians using Fleiss' kappa and between veterinarians of similar experience levels in the five subgroups using Cohen's unweighted (k) and Cohen's linear weighted kappa (Ck). Intraobserver agreement was similarly calculated for each reviewer using 22 repeated video clips. RESULTS: Overall interobserver agreement using ordinal scales was fair (k = 0.27, 95% CI 0.22-0.31) to moderate (mean weighted Ck = 0.57, 95% CI 0.46-0.69) depending on statistical methodology used. Using the dichotomous classification, interobserver agreement was good (k = 0.7, 95% CI 0.63-0.77). Overall intraobserver agreement using ordinal scales was fair (mean k = 0.26, 95% CI 0.14-0.38) to good (mean Ck = 0.61, 95% CI 0.50-0.71); and for the dichotomous reclassification it was good (k = 0.73, 95% CI 0.59-0.87). Experience level differences were identified. MAIN LIMITATIONS: The low number of veterinarians in each experience subgroup. CONCLUSIONS: Subjectivity exists in arytenoid function grading, despite the existence of a well-defined scale. Agreement variation exists depending on the grading scales and statistical methods used for analysis. Future studies pre- and post veterinarian training are indicated to determine if agreement can be improved.

Extraction of unadjusted estimates of prognostic association for meta-analysis: simulation methods as good alternatives to trend and direct method estimation.

OBJECTIVES: Systematic reviews and meta-analysis are the standard methods to assess the association between prognostic markers and major events/conditions. However, the summary measures reported are not always explicitly presented and therefore different indirect methods of extracting estimates have been proposed. The aim of this study is to present two new alternative methods for obtaining summary statistics to be included in a meta-analysis of prognostic studies based on simulating individual patient data and to compare them with the already known generalized least squares for trend (glst) estimation method and direct method. STUDY DESIGN AND SETTINGS: We have checked the performance of these methods using a between study comparison, including 122 studies, and a within study comparison, based on data from one of the studies. RESULTS: The results obtained in this study show that glst estimation method appears to overestimate the effect size when reported information is incomplete. For the within-study comparison, the closest approximation to the direct estimates was obtained using the approach based on simulating individual patient data. CONCLUSION: The proposed simulation methods are a good alternative when other well-known indirect methods cannot be used.

Antibody-Induced Internalization of the Human Respiratory Syncytial Virus Fusion Protein.

Respiratory syncytial virus (RSV) infections remain a major cause of respiratory disease and hospitalizations among infants. Infection recurs frequently and establishes a weak and short-lived immunity. To date, RSV immunoprophylaxis and vaccine research is mainly focused on the RSV fusion (F) protein, but a vaccine remains elusive. The RSV F protein is a highly conserved surface glycoprotein and is the main target of neutralizing antibodies induced by natural infection. Here, we analyzed an internalization process of antigen-antibody complexes after binding of RSV-specific antibodies to RSV antigens expressed on the surface of infected cells. The RSV F protein and attachment (G) protein were found to be internalized in both infected and transfected cells after the addition of either RSV-specific polyclonal antibodies (PAbs) or RSV glycoprotein-specific monoclonal antibodies (MAbs), as determined by indirect immunofluorescence staining and flow-cytometric analysis. Internalization experiments with different cell lines, well-differentiated primary bronchial epithelial cells (WD-PBECs), and RSV isolates suggest that antibody internalization can be considered a general feature of RSV. More specifically for RSV F, the mechanism of internalization was shown to be clathrin dependent. All RSV F-targeted MAbs tested, regardless of their epitopes, induced internalization of RSV F. No differences could be observed between the different MAbs, indicating that RSV F internalization was epitope independent. Since this process can be either antiviral, by affecting virus assembly and production, or beneficial for the virus, by limiting the efficacy of antibodies and effector mechanism, further research is required to determine the extent to which this occurs in vivo and how this might impact RSV replication.IMPORTANCE Current research into the development of new immunoprophylaxis and vaccines is mainly focused on the RSV F protein since, among others, RSV F-specific antibodies are able to protect infants from severe disease, if administered prophylactically. However, antibody responses established after natural RSV infections are poorly protective against reinfection, and high levels of antibodies do not always correlate with protection. Therefore, RSV might be capable of interfering, at least partially, with antibody-induced neutralization. In this study, a process through which surface-expressed RSV F proteins are internalized after interaction with RSV-specific antibodies is described. One the one hand, this antigen-antibody complex internalization could result in an antiviral effect, since it may interfere with virus particle formation and virus production. On the other hand, this mechanism may also reduce the efficacy of antibody-mediated effector mechanisms toward infected cells.

Is being resolute better than being pragmatic when it comes to breastfeeding? Longitudinal qualitative study investigating experiences of women intending to breastfeed using the Theoretical Domains Framework.

Background: In the UK, initiating then discontinuing breastfeeding before two weeks post-partum is common. The aim of this longitudinal qualitative study was to explore which psychosocial factors may influence discontinuation. Methods: A sample of 10 pregnant women intending to breastfeed were recruited. A longitudinal qualitative design was used to capture views prior to and two weeks following birth. Semi-structured interviews were conducted underpinned by the Theoretical Domains Framework to explore a comprehensive list of psychosocial factors. Results: Four women discontinued breastfeeding at the time of the second interview. Pre-partum differences were identified between maintainers and discontinuers; discontinuers appeared to have stronger intentions to breastfeed based on their self-determination, self-confidence and perception of fewer barriers to breastfeeding. Post-partum, discontinuers highlighted how they felt physically unable to carry on; their feeding experiences elicited negative emotions and pain. Negative emotions appeared to be exacerbated by original breastfeeding beliefs and advice given by healthcare professionals. Conclusions: The women in this study who discontinued breastfeeding showed less cognitive flexibility, which appeared to exacerbate post-partum emotional distress, when they encountered difficulties. Women with strong intentions and self-determination might benefit from support in anticipating potential barriers and identifying ways of overcoming them.

Association between sesamoiditis, subclinical ultrasonographic suspensory ligament branch change and subsequent clinical injury in yearling Thoroughbreds.

REASONS FOR PERFORMING STUDY: Sesamoiditis is a common radiological finding in yearling Thoroughbreds. The condition is believed to be associated with suspensory ligament branch injury (SLBI), which is known to affect racing performance. The presence of subclinical suspensory ligament branch change (SSLBC) in untrained yearlings has not been investigated. Associations between sesamoiditis, SSLBC and subsequent SLBI would allow more accurate prognoses to be made regarding the development of SLBI. They could also provide opportunity for intervention and prevention of SLBI. OBJECTIVES: To test our hypotheses that untrained yearling Thoroughbreds with sesamoiditis would be more likely to have ultrasonographic findings of SSLBC and those horses with concurrent sesamoiditis and SSLBC would be more likely to develop clinical suspensory ligament branch injury with training. STUDY DESIGN: Prospective, cohort, observational study. METHODS: Yearling Thoroughbreds located at a single training centre were evaluated at the onset of their training careers and for the next 9 months. Radiographic and ultrasonographic examination of bilateral forelimb proximal sesamoid bones and suspensory ligament branches was performed. RESULTS: Fifty horses were eligible, resulting in 200 forelimb sesamoid/suspensory ligament branch pairs. A significant relationship existed between possibly significant (PS) sesamoiditis and PS SSLBC (P<0.001). The odds ratio of sesamoids with PS sesamoiditis also demonstrating concurrent PS SSLBC was 5.1 (95% confidence interval 2.68-9.70, P<0.001). A significant relationship also existed between the concurrent presence of PS sesamoiditis and PS SSLBC and the subsequent development of clinical signs of SLBI (P<0.001, odds ratio 11.7, 95% confidence interval 4.1-33.4). CONCLUSIONS: The associations identified in this study highlight the importance of ultrasonographic examination of suspensory ligament branches in horses with PS sesamoiditis. This information should allow more accurate prognostic advice regarding potential SLBI development and also provide opportunities for intervention and prevention of clinical SLBI. THE SUMMARY IS AVAILABLE IN CHINESE - SEE SUPPORTING INFORMATION.

The effect of insertional suspensory branch desmitis on racing performance in juvenile Thoroughbred racehorses.

REASONS FOR PERFORMING THE STUDY: Limited information exists regarding the prognosis for juvenile racehorses sustaining injury to the suspensory ligament branch insertion (JISBI). OBJECTIVES: To investigate the effect of JISBI on racing performance; and to assess whether the severity of JISBI is prognostically important. STUDY DESIGN: Retrospective cohort study. METHODS: Records were reviewed for 896 juvenile Thoroughbreds in training, to identify horses with JISBI limited to one branch (cases). The ability of cases to start a race was compared to their cohorts. Race records of maternal siblings were compared to cases. RESULTS: The prevalence of JISBI for this population was 9.5%. Cohorts were 3.2 times more likely to start as a 2-year-old and 3.6 times more likely to start as a 3-year-old compared to horses with JISBI. Of 58 cases that were compared to maternal siblings, the total earnings per start (EPS), 2- and 3-year-old EPS were all reduced (P<0.01). Cases raced a mean of 3.8 times compared to 7.4 races for controls over the study period and were 113.2 days older by the time of first start (P<0.01). 'Speed figures' and EPS were, however, similar between cases that had raced and controls. Cases with a moderate-severe lesion (≥ Grade 2) were at significantly greater risk of reinjury than mild cases (P<0.05). CONCLUSIONS: JISBI causes decreased racing ability as a 2-year-old. Mild cases perform similarly to controls by their 3-year-old season, but more severe cases demonstrate reduced ability as a 3-year-old, with an increased likelihood of reinjury. Although the wastage was higher in case horses with JISBI, individual cases that make it to a race have similar earnings per start as their controls.

Do radiographic signs of sesamoiditis in yearling Thoroughbreds predispose the development of suspensory ligament branch injury?

REASONS FOR PERFORMING STUDY: Sesamoiditis is believed to be associated with injury to the suspensory branch attachment and is a common radiographic finding in yearling Thoroughbreds. No study has investigated relationships between yearling sesamoiditis and subsequent development of suspensory ligament branch injury (SLBI) in early racehorse training. OBJECTIVES: To establish the prevalence of SLBI within a population of juvenile training racehorses and retrospectively investigate relationships between clinical signs of SLBI and sesamoiditis to determine if sesamoiditis is a risk factor for clinical suspensory branch injury. STUDY DESIGN: Retrospective case control study. METHODS: Presale radiographs of 291 clinically normal yearling Thoroughbreds were reviewed for sesamoiditis and graded using 3 objective scales. Medical records encompassing the first year of race training were reviewed to identify cases of SLBI and the remaining unaffected controls from the cohort. Statistical analysis determined the relationship between sesamoiditis and the development of SLBI during training. RESULTS: The prevalence of SLBI was 9.97%. Case and control horses demonstrated a similar prevalence of sesamoiditis overall but SLBI cases demonstrated increased severity of sesamoiditis on yearling radiographs compared with unaffected controls. This significant relationship between sesamoiditis and cases of SLBI was only observed using one of the 3 scales. Using that scale, sesamoids exhibiting more pronounced sesamoiditis on yearling radiographs were 5 times more likely to develop SLBI in the adjacent suspensory branch (OR 4.56, 95% CI 2.18-9.53, P = 0.0001). CONCLUSIONS: This study reveals that the grading scale used is important when providing prognostic advice on the significance of radiographic signs of sesamoiditis. Evidence of significant sesamoiditis implies a 5 times greater risk of developing clinical SLBI with the onset of training. Clinicians should be aware that sesamoiditis may be an indicator of future SLBI in yearlings which are clinically normal at the time of sale.

Does periosteal scraping of the third metacarpal bone reduce the incidence of 'bucked shins' in young Thoroughbred racehorses?

REASONS FOR PERFORMING STUDY: The occurrence of bucked shins in young Thoroughbred racehorses in North America is high. Although an altered training regime has demonstrated a significant decrease in this condition, trainers can be opposed to altering something as fundamental as their training routine. Periosteal scraping of the third metacarpal bone (McIII) is a putative prophylactic technique used to prevent bucked shins; therefore, a study to investigate the validity of the procedure is warranted. OBJECTIVES: To investigate whether prophylactic McIII scraping: 1) reduces the incidence of bucked shins in juvenile Thoroughbred horses at race speeds (breeze); and 2) allows increased cumulative breeze miles before the onset of disease. STUDY DESIGN: Nonrandomised prospective clinical study. METHODS: One hundred and seventy yearling Thoroughbreds from one farm, under one trainer, were enrolled in this study over one training season; 85 horses were treated and 85 horses were control animals. Horses were observed for bucked shins over 5 cumulative breeze miles. The objectives were evaluated by comparing incidence rates and Kaplan-Meier plots. RESULTS: The incidence rate for bucked shins was 0.059 cases per breezed mile in the treatment group, compared with 0.103 cases per breezed mile in the control group. Comparison of Kaplan-Meier plots of breeze miles for the 2 groups demonstrated a significant difference between groups (P = 0.035). Horses that developed bucked shins following periosteal shin scraping breezed an average of 3.52 miles before the onset of disease, compared to 2.50 miles for horses not prophylactically treated (P = 0.005). CONCLUSIONS: Periosteal McIII scraping reduced the incidence rate of bucked shins. The procedure allowed treated horses to breeze greater cumulative distances before an incident but failed to prevent the disease over the long term. Further investigation into this commonly used prophylactic technique is required.

Cancer outcomes and all-cause mortality in adults allocated to metformin: systematic review and collaborative meta-analysis of randomised clinical trials.

AIMS/HYPOTHESIS: Observational studies suggest that metformin may reduce cancer risk by approximately one-third. We examined cancer outcomes and all-cause mortality in published randomised controlled trials (RCTs). METHODS: RCTs comparing metformin with active glucose-lowering therapy or placebo/usual care, with minimum 500 participants and 1-year follow-up, were identified by systematic review. Data on cancer incidence and all-cause mortality were obtained from publications or by contacting investigators. For two trials, cancer incidence data were not available; cancer mortality was used as a surrogate. Summary RRs, 95% CIs and I (2)statistics for heterogeneity were calculated by fixed effects meta-analysis. RESULTS: Of 4,039 abstracts identified, 94 publications described 14 eligible studies. RRs for cancer were available from 11 RCTs with 398 cancers during 51,681 person-years. RRs for all-cause mortality were available from 13 RCTs with 552 deaths during 66,447 person-years. Summary RRs for cancer outcomes in people randomised to metformin compared with any comparator were 1.02 (95% CI 0.82, 1.26) across all trials, 0.98 (95% CI 0.77, 1.23) in a subgroup analysis of active-comparator trials and 1.36 (95% CI 0.74, 2.49) in a subgroup analysis of placebo/usual care comparator trials. The summary RR for all-cause mortality was 0.94 (95% CI 0.79, 1.12) across all trials. CONCLUSIONS/INTERPRETATION: Meta-analysis of currently available RCT data does not support the hypothesis that metformin lowers cancer risk by one-third. Eligible trials also showed no significant effect of metformin on all-cause mortality. However, limitations include heterogeneous comparator types, absent cancer data from two trials, and short follow-up, especially for mortality.

Test Not Talk screening for asymptomatic men.

This audit reviews the first year's experience within a rapid comprehensive sexually transmitted infection (STI) and HIV screening for asymptomatic men in a small-integrated sexual health clinic in outer London. Men requesting STI/HIV screening only were offered symptom self-assessment, blood tests for syphilis and HIV, and first void urine tests for chlamydia and gonorrhoea. Of 468 available appointments, 337 were made (72%) and 303 were kept (80%). Of the 303 attendances, 264 (87%) were first-ever attendances. Of the 303 men seen, 295 (97.4%) underwent chlamydia and gonorrhoea testing, while 246 (80.9%) were tested for syphilis and HIV. No new HIV diagnoses were made. One patient was diagnosed with late latent syphilis and one had asymptomatic gonorrhoea, while 20 (6.6%) diagnoses of chlamydia were made. We believe that Test Not Talk clinics offer a good approach to rapid screening of asymptomatic men and to meet their sexual health needs.

Effects of interactions among wave aberrations on optical image quality.

Wave aberrations degrade the optical quality of the eye relative to the diffraction limit, but there are situations in which having slightly aberrated optics can provide some relative visual benefits. This fact led us to consider whether interactions among aberrations in the eye's wavefront produce an advantage for image quality relative to wavefronts with randomized combinations of aberrations with the same total RMS error. Total ocular wave aberrations from two experimental groups and corneal wave aberrations from one group were measured and expressed as Zernike polynomial expansions through the seventh-order. In a series of Monte Carlo simulations, modulation transfer functions (MTFs) for the measured wave aberrations were compared to distributions of artificial MTFs for wavefronts created by randomizing the sign or orientation of the aberrations, while maintaining the RMS error within each Zernike order. In a control condition, "synthetic" model eyes were produced by choosing each individual aberration term at random from individuals in the experimental group, and again MTFs were compared for original and randomized signs. Results were summarized by the MTF ratio: real MTF/mean simulated MTF, as a function of spatial frequency. For a 6mm pupil, the mean MTF ratio for total ocular aberrations was greater than 1.0 up to 60 cycles per degree, suggesting that the eye's aberrations are not independent and that there may be a positive functional consequences to their interrelations. This positive relation did not hold for corneal aberrations alone, or for the synthetic eyes.

Effect of body size on gastric emptying using the 13C-octanoic acid breath test.

The 13C-octanoic acid breath test (OABT) may be a useful non-invasive method for assessing the rate of gastric emptying in dogs. The aim of this study was to determine whether an association exists between body size and rate of gastric emptying in dogs. Fifty-five dogs ranging from 6 to 39 kg were recruited and rate of gastric emptying was assessed using the OABT. The time to peak 13CO2 excretion (tmax) and half-dose recovery time (t1/2) were calculated. The OABT was simple to perform and well tolerated by the dogs. Mean (sd) tmax was 2.67 hours (0.6) and mean t1/2 was 3.38 hours (0.79). Inter-individual variation in the rate of gastric emptying was 23.3 per cent for t1/2 and 22.5 per cent for tmax. No association was detected between the rate of gastric emptying and body surface area, mass, age, sex or test operator. The OABT may be a useful non-invasive and non-radioactive test for assessment of the rate of gastric emptying in dogs in clinical practice.

A review of methods for assessment of the rate of gastric emptying in the dog and cat: 1898-2002.

Gastric emptying is the process by which food is delivered to the small intestine at a rate and in a form that optimizes intestinal absorption of nutrients. The rate of gastric emptying is subject to alteration by physiological, pharmacological, and pathological conditions. Gastric emptying of solids is of greater clinical significance because disordered gastric emptying rarely is detectable in the liquid phase. Imaging techniques have the disadvantage of requiring restraint of the animal and access to expensive equipment. Radiographic methods require administration of test meals that are not similar to food. Scintigraphy is the gold standard method for assessment of gastric emptying but requires administration of a radioisotope. Magnetic resonance imaging has not yet been applied for assessment of gastric emptying in small animals. Ultrasonography is a potentially useful, but subjective, method for assessment of gastric emptying in dogs. Gastric tracer methods require insertion of gastric or intestinal cannulae and are rarely applied outside of the research laboratory. The paracetamol absorption test has been applied for assessment of liquid phase gastric emptying in the dog, but requires IV cannulation. The gastric emptying breath test is a noninvasive method for assessment of gastric emptying that has been applied in dogs and cats. This method can be carried out away from the veterinary hospital, but the effects of physiological and pathological abnormalities on the test are not known. Advances in technology will facilitate the development of reliable methods for assessment of gastric emptying in small animals.

Microlissencephaly with cardiac, spinal and urogenital defects.

We describe two children with a brain defect similar to that described as 'microlissencephaly', as defined in Barkovich et aL [(1998) Neuroped 29: 113-119]. Concomitant malformations (cardiac, spinal, urogenital) may represent components of a wider syndrome complex; alternatively, or additionally, there may have been a valproate teratogenic effect. The inheritance is likely to be autosomal recessive, although X-linkage cannot be excluded.

Age-related changes in monochromatic wave aberrations of the human eye.

PURPOSE: To investigate the relations between age and the optical aberrations of the whole eye. The eye's optical quality, as measured by the modulation transfer function (MTF), degrades with age, but the MTF does not provide a means to assess the contributions of individual aberrations, such as coma, spherical aberration, and other higher order aberrations to changes in optical quality. The method used in this study provides measures of individual aberrations and overall optical quality. METHODS: Wave aberrations in 38 subjects were measured psychophysically using a spatially resolved refractometer. Data were fit with Zernike polynomials up to the seventh order to provide estimates of 35 individual aberration terms. MTFs and root mean square (RMS) wavefront errors were calculated. Subjects ranged in age from 22.9 to 64.5 years, with spherical equivalent corrections ranging from +0.5 to -6.0 D. RESULTS: Overall RMS wavefront error (excluding tilts, astigmatism, and defocus) was significantly positively correlated with age (r = 0.33, P = 0.042). RMS error for the highest order aberrations measured (fifth through seventh order) showed a strong positive correlation with age (r = 0.57, P = 0.0002). Image quality, as quantified by the MTF, also degraded with age. CONCLUSIONS: Wave aberrations of the eye increase with age. This increase is consistent with the loss of contrast sensitivity with age observed by other investigators.

Storybook-based communication intervention for girls with Rett syndrome and their mothers.

PURPOSE: Storybook reading provides a natural language learning context in which to support early symbolic communication. In this study, we explored the impact of (1) resting hand splints, (2) light tech augmentative communication systems such as voice-output devices and symbols, and (3) very basic parent training on the symbolic communication and labelling behaviours of six girls with Rett syndrome. METHOD: Mothers and daughters were videotaped as they read familiar and unfamiliar storybooks in their homes. RESULTS: Group and individual data collected from the six girls indicated that they became more active and successful participants in the interactions during storybook reading. The girls employed a wider range of communication modes and increased the frequency of their labelling. Familiar storybook reading encouraged greater symbolic communication than unfamiliar storybooks in half the girls. CONCLUSION: This study suggests that motivated parents may not require expensive technologies or lengthy training in order to enhance their children's early communication and participation in storybook reading.

ON and OFF S-cone pathways have different long-wave cone inputs.

Three experiments compared thresholds for S-cone increments and decrements under steady and transient adaptation conditions, to investigate whether stimuli of both polarities are detected by the same cone-opponent psychophysical mechanism. The results could not be accounted for by a standard model of the S-cone detection pathway [Polden & Mollon (1980) Proceedings of the Royal Society of London, B, 210, 235-272]. In particular, a transient tritanopia detection paradigm that measured threshold elevation following the offset of long-wavelength fields produced different field sensitivities for S-cone increment and decrement tests. The decrement field sensitivity function was shifted to shorter wavelengths relative to the increment function. L-cone opponency is apparently stronger for S-cone increments than for decrements. The most plausible substrates of the two different psychophysical detection mechanisms are the ON and OFF channels. The results suggest that S-ON (bistratified) and S-OFF ganglion cells receive different relative amounts of L- and M-cone input.