A Customisable Data Acquisition System for Open-Source Hyperspectral Imaging

Hyperspectral imagers, or imaging spectrometers, are used in many remote sensing environmental studies in fields such as agriculture, forestry, geology, and hydrology. In recent years, compact hyperspectral imagers were developed using commercial-off-the-shelf components, but there are not yet any off-the-shelf data acquisition systems on the market to deploy them. The lack of a self-contained data acquisition system with navigation sensors is a challenge that needs to be overcome to successfully deploy these sensors on remote platforms such as drones and aircraft. Our work is the first successful attempt to deploy an entirely open-source system that is able to collect hyperspectral and navigation data concurrently for direct georeferencing. In this paper, we describe a low-cost, lightweight, and deployable data acquisition device for the open-source hyperspectral imager (OpenHSI). We utilised commercial-off-the-shelf hardware and open-source software to create a compact data acquisition device that can be easily transported and deployed. The device includes a microcontroller and a custom-designed PCB board to interface with ancillary sensors and a Raspberry Pi 4B/NVIDIA Jetson. We demonstrated our data acquisition system on a Matrice M600 drone at a beach in Sydney, Australia, collecting timestamped hyperspectral, navigation, and orientation data in parallel. Using the navigation and orientation data, the hyperspectral data were georeferenced. While the entire system including the pushbroom hyperspectral imager and housing weighed 735 g, it was designed to be easy to assemble and modify. This low-cost, customisable, deployable data acquisition system provides a cost-effective solution for the remote sensing of hyperspectral data for everyone.

Components of leaf-trait variation along environmental gradients

Leaf area (LA), mass per area (LMA), nitrogen per unit area (N_area ) and the leaf-internal to ambient CO₂ ratio (χ) are fundamental traits for plant functional ecology and vegetation modelling. Here we aimed to assess how their variation, within and between species, tracks environmental gradients. Measurements were made on 705 species from 116 sites within a broad north-south transect from tropical to temperate Australia. Trait responses to environment were quantified using multiple regression; within- and between-species responses were compared using analysis of covariance and trait-gradient analysis. Leaf area, the leaf economics spectrum (indexed by LMA and N_area ) and χ (from stable carbon isotope ratios) varied almost independently among species. Across sites, however, χ and LA increased with mean growing-season temperature (mGDD₀ ) and decreased with vapour pressure deficit (mVPD₀ ) and soil pH. LMA and N_area showed the reverse pattern. Climate responses agreed with expectations based on optimality principles. Within-species variability contributed < 10% to geographical variation in LA but > 90% for χ, with LMA and N_area intermediate. These findings support the hypothesis that acclimation within individuals, adaptation within species and selection among species combine to create predictable relationships between traits and environment. However, the contribution of acclimation/adaptation vs species selection differs among traits.

Cardiac Leiomyosarcoma in a Cat Presenting for Bilateral Renal Neoplasia

A 10-year-old neutered female domestic longhair cat was presented to a tertiary care veterinary hospital for evaluation of a right renal mass that was identified incidentally on abdominal radiographs and classified further as a sarcoma based on fine needle aspiration cytology. Further diagnostic workup, including ultrasound and cytology, identified a sarcoma in the left kidney. After approximately 1 month of conservative medical management, the clinical condition deteriorated and the cat was humanely destroyed. Post-mortem examination confirmed bilateral renal masses with multifocal infarction and extensive necrosis, and further identified a large mass at the apex of the heart as well as multiple pulmonary nodules. Microscopical examination of the masses identified a population of poorly-differentiated neoplastic spindle cells, consistent with sarcoma. Immunohistochemically, the neoplastic cells expressed smooth muscle actin and muscle-specific actin, but were negative for myoglobin and factor VIII. Phosphotungstic acid-haematoxylin staining was unable to identify cross-striations in the neoplastic cells. Based on these results and the pattern of lesion distribution, the cat was diagnosed with cardiac leiomyosarcoma with pulmonary and bilateral renal metastasis.

The validity of optimal leaf traits modelled on environmental conditions

The ratio of leaf intercellular to ambient CO₂ (χ) is modulated by stomatal conductance (g_s ). These quantities link carbon (C) assimilation with transpiration, and along with photosynthetic capacities (V_cmax and J_max ) are required to model terrestrial C uptake. We use optimization criteria based on the growth environment to generate predicted values of photosynthetic and water-use efficiency traits and test these against a unique dataset. Leaf gas-exchange parameters and carbon isotope discrimination were analysed in relation to local climate across a continental network of study sites. Sun-exposed leaves of 50 species at seven sites were measured in contrasting seasons. Values of χ predicted from growth temperature and vapour pressure deficit were closely correlated to ratios derived from C isotope (δ¹³ C) measurements. Correlations were stronger in the growing season. Predicted values of photosynthetic traits, including carboxylation capacity (V_cmax ), derived from δ¹³ C, growth temperature and solar radiation, showed meaningful agreement with inferred values derived from gas-exchange measurements. Between-site differences in water-use efficiency were, however, only weakly linked to the plant's growth environment and did not show seasonal variation. These results support the general hypothesis that many key parameters required by Earth system models are adaptive and predictable from plants' growth environments.

Towards a universal model for carbon dioxide uptake by plants

Gross primary production (GPP)-the uptake of carbon dioxide (CO₂) by leaves, and its conversion to sugars by photosynthesis-is the basis for life on land. Earth System Models (ESMs) incorporating the interactions of land ecosystems and climate are used to predict the future of the terrestrial sink for anthropogenic CO₂¹ . ESMs require accurate representation of GPP. However, current ESMs disagree on how GPP responds to environmental variations ^1,2 , suggesting a need for a more robust theoretical framework for modelling ^3,4 . Here, we focus on a key quantity for GPP, the ratio of leaf internal to external CO₂ (χ). χ is tightly regulated and depends on environmental conditions, but is represented empirically and incompletely in today's models. We show that a simple evolutionary optimality hypothesis ^5,6 predicts specific quantitative dependencies of χ on temperature, vapour pressure deficit and elevation; and that these same dependencies emerge from an independent analysis of empirical χ values, derived from a worldwide dataset of >3,500 leaf stable carbon isotope measurements. A single global equation embodying these relationships then unifies the empirical light-use efficiency model ⁷ with the standard model of C₃ photosynthesis ⁸ , and successfully predicts GPP measured at eddy-covariance flux sites. This success is notable given the equation's simplicity and broad applicability across biomes and plant functional types. It provides a theoretical underpinning for the analysis of plant functional coordination across species and emergent properties of ecosystems, and a potential basis for the reformulation of the controls of GPP in next-generation ESMs.

Abstract 961: Inhibitors of fibrosis and TGF-beta delay tumor xenograft growth and reduce ascites in ovarian cancer models

Background: Most ovarian cancer (OC) patients present with advanced disease and ultimately develop chemo-resistant relapses. Stroma plays a significant role in OC behavior including invasiveness, fibrosis and chemoresistance. TGF-β is important for crosstalk between stroma and cancer cells, and stromal activation in cancer has similarities to matrix remodeling in fibrosis. We have shown that TGF-β and fibrosis-inhibitors can suppress OC cell proliferation, migration and invasion. Such inhibitors are available for clinical use, and we have begun to test their efficacy in OC in vivo.

Methods: Animal experiments were approved by Mayo Clinic IACUC. Intraperitoneal xenograft models were derived from OVCAR8 (5×106) cells (OV8-CDX) or 0.1 gm OC patient tumor tissue (PDX) in NSG mice. OV8-CDX and PDX PH003 (an aggressive, chemoresistant and ascites-prone model) (n=5-10 mice/arm) were treated with 2 agents and compared to untreated controls (C): 1) C vs. the fibrosis inhibitor Pirfenidone (P, 200 mg/kg, BID, provided by Genentech); 2) C vs. TGF-β receptor I inhibitor Galunisertib (G, 75 mg/kg, BID, provided by Eli Lily). Mice were pretreated for 2 days before xenografting and treated for 4 weeks with ultrasound (US) to measure tumor growth. At day (d) 28, we i) collected tumor (OV8-CDX); or ii) observed until progression (PH003, PH053). OV8-CDX tumors were used for target gene analysis.

Results: P treatment delayed tumor growth in OV8-CDX relative to control (C): tumors established in 0/5 (P) vs. 1/5 (C), and 1/5 (P) vs. 4/5 (C) of mice at d14 and d28, respectively. The reduced tumor weight (g) at d28 was also confirmed (0.20±0.10 vs. 0.54±0.23, p=0.02). Similarly, P treatment in PH003 inhibited the tumor growth (tumor area (cm2) at d28: 0.74±0.43 vs. 1.04±0.51, p=0.28), ascites development (volume (ml): 1.14±0.54 vs. 3.37±0.62, p=0.05) and prolonged survival time (p=0.04).

G treatment was also associated with delayed tumor establishment in OV8-CDX relative to C: tumors presented in 0/5 (G) vs. 1/5 (C), and 1/5 (G) vs. 4/5 (C) of mice at d14 and d28, respectively. Associated d28 tumor weight was significantly reduced (0.20±0.10 vs. 0.54±0.23, p=0.02) as well. For PH003, G treatment was associated with delayed tumor growth (tumor area at d28: 0.57±0.27 vs. 1.04±0.51, p=0.05), a marked reduction in ascites (volume: 1.25±0.56 vs. 3.37±0.62, p=0.05) and a prolonged survival time (p=0.04)

We identified down-regulation of TGF-β signaling-related genes (e.g. TGFB1, TGFBR2) and fibrosis-related biomarkers (e.g. FAP, COL11A1) following drug treatment confirming inhibition of relevant pathways.

Conclusion: We report that 2 currently available inhibitors targeting either fibrosis or TGF-β appear to have efficacy in vivo and delay tumor growth in OC PDX models. These results suggest promise for a strategy of targeting the stromal component of OC.

Citation Format: Qing Zhang, Xiaonan Hou, Bradley J. Evans, John J. Weroha, William A. Cliby. Inhibitors of fibrosis and TGF-beta delay tumor xenograft growth and reduce ascites in ovarian cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 961. doi:10.1158/1538-7445.AM2017-961

Bioclimatic transect networks: Powerful observatories of ecological change

Transects that traverse substantial climate gradients are important tools for climate change research and allow questions on the extent to which phenotypic variation associates with climate, the link between climate and species distributions, and variation in sensitivity to climate change among biomes to be addressed. However, the potential limitations of individual transect studies have recently been highlighted. Here, we argue that replicating and networking transects, along with the introduction of experimental treatments, addresses these concerns. Transect networks provide cost‐effective and robust insights into ecological and evolutionary adaptation and improve forecasting of ecosystem change. We draw on the experience and research facilitated by the Australian Transect Network to demonstrate our case, with examples, to clarify how population‐ and community‐level studies can be integrated with observations from multiple transects, manipulative experiments, genomics, and ecological modeling to gain novel insights into how species and systems respond to climate change. This integration can provide a spatiotemporal understanding of past and future climate‐induced changes, which will inform effective management actions for promoting biodiversity resilience.

Treatment outcomes and prognostic factors of feline splenic mast cell tumors: A multi-institutional retrospective study of 64 cases

BACKGROUND

Mast cell tumors (MCT) are common splenic tumors in cats, but there is limited information on treatment outcomes of cats with this disease.

MATERIALS AND METHODS

This retrospective study evaluated treatment outcomes in 64 cats with splenic MCT. Cats were categorized into the following treatment groups: splenectomy (A, n = 20); splenectomy with chemotherapy (B, n = 20); chemotherapy alone (C, n = 15); or supportive care (D, n = 9).

RESULTS

Median tumor specific survival (MTSS) was: 856, 853, 244, 365 days for groups A, B, C, and D, respectively. The MTSS was not significantly different between the 4 groups. However, comparing cats that had splenectomy (A and B) versus those that did not (C and D), the MTSS was 856 and 342 days, respectively (p=0.008). None of the prognostic factors analyzed significantly influenced survival.

CONCLUSION

Splenectomy (+/- chemotherapy) significantly prolongs survival in cats with mast cell tumors. The role of chemotherapy remains unknown.

A test of the 'one-point method' for estimating maximum carboxylation capacity from field-measured, light-saturated photosynthesis

Simulations of photosynthesis by terrestrial biosphere models typically need a specification of the maximum carboxylation rate (Vcmax ). Estimating this parameter using A-Ci curves (net photosynthesis, A, vs intercellular CO2 concentration, Ci ) is laborious, which limits availability of Vcmax data. However, many multispecies field datasets include net photosynthetic rate at saturating irradiance and at ambient atmospheric CO2 concentration (Asat ) measurements, from which Vcmax can be extracted using a 'one-point method'. We used a global dataset of A-Ci curves (564 species from 46 field sites, covering a range of plant functional types) to test the validity of an alternative approach to estimate Vcmax from Asat via this 'one-point method'. If leaf respiration during the day (Rday ) is known exactly, Vcmax can be estimated with an r(2) value of 0.98 and a root-mean-squared error (RMSE) of 8.19 μmol m(-2) s(-1) . However, Rday typically must be estimated. Estimating Rday as 1.5% of Vcmax, we found that Vcmax could be estimated with an r(2) of 0.95 and an RMSE of 17.1 μmol m(-2) s(-1) . The one-point method provides a robust means to expand current databases of field-measured Vcmax , giving new potential to improve vegetation models and quantify the environmental drivers of Vcmax variation.

Fire in Australian savannas: from leaf to landscape

Savanna ecosystems comprise 22% of the global terrestrial surface and 25% of Australia (almost 1.9 million km2) and provide significant ecosystem services through carbon and water cycles and the maintenance of biodiversity. The current structure, composition and distribution of Australian savannas have coevolved with fire, yet remain driven by the dynamic constraints of their bioclimatic niche. Fire in Australian savannas influences both the biophysical and biogeochemical processes at multiple scales from leaf to landscape. Here, we present the latest emission estimates from Australian savanna biomass burning and their contribution to global greenhouse gas budgets. We then review our understanding of the impacts of fire on ecosystem function and local surface water and heat balances, which in turn influence regional climate. We show how savanna fires are coupled to the global climate through the carbon cycle and fire regimes. We present new research that climate change is likely to alter the structure and function of savannas through shifts in moisture availability and increases in atmospheric carbon dioxide, in turn altering fire regimes with further feedbacks to climate. We explore opportunities to reduce net greenhouse gas emissions from savanna ecosystems through changes in savanna fire management.

Description of a new octoploid frog species (Anura: Pipidae: Xenopus) from the Democratic Republic of the Congo, with a discussion of the biogeography of African clawed frogs in the Albertine Rift

We describe a new octoploid species of African clawed frog (Xenopus) from the Lendu Plateau in the northern Albertine Rift of eastern Democratic Republic of the Congo. This species is the sister taxon of Xenopus vestitus (another octoploid), but is distinguished by a unique morphology, vocalization and molecular divergence in mitochondrial and autosomal DNA. Using a comprehensive genetic sample, we provide new information on the species ranges and intra-specific diversity of African clawed frogs from the Albertine Rift, including the details of a small range extension for the critically endangered Xenopus itombwensis and previously uncharacterized variation in Xenopus laevis. We also detail a new method for generating cytogenetic preparations in the field that can be stored at room temperature for up to 3 weeks. While extending our understanding of the extant diversity in the Albertine Rift, this new species highlights components of species diversity in ancestral African clawed frogs that are not represented by known extant descendants.

The inflammatory effect of cardiopulmonary bypass on leukocyte extravasation in vivo

OBJECTIVE

Extravascular trafficking of leukocytes into organs is thought to play a major role in the pathophysiologic mechanisms of the inflammatory response to cardiopulmonary bypass, yet leukocyte extravasation is difficult to study clinically. Here we have tested the hypothesis that leukocyte emigration into skin blisters can provide a way to monitor the inflammatory effect of cardiopulmonary bypass that allows testing of anti-inflammatory interventions (exemplified by aprotinin).

METHODS

Patients undergoing primary elective coronary artery bypass grafting (n = 14) were randomized into 2 equal groups to receive saline infusion during cardiopulmonary bypass (control group) or high-dose aprotinin. Experimental skin blisters (in duplicate) were induced on the forearm by means of topical application of the vesicant cantharidin, and blister fluid was sampled at 5 hours postoperatively. Inflammatory leukocyte subsets in blister fluid were analyzed by means of flow cytometry by using expression of CD11b and CD62L as a phenotypic marker of activation.

RESULTS

In the control group of patients, cardiopulmonary bypass surgery triggered a 381% increase in leukocyte extravasation into the skin compared with reference blisters carried out before surgical intervention, with neutrophil (P = .014), monocyte (P = .014), and eosinophil (P = .009) levels all statistically significantly increased. In the aprotinin group there was no statistically significant increase during cardiopulmonary bypass surgery in any inflammatory leukocyte subset. The activation phenotype of extravascular leukocytes was not significantly altered between surgical groups.

CONCLUSIONS

This study introduces the cantharidin blister technique as a powerful new research tool for analyzing the inflammatory effect of cardiopulmonary bypass in vivo. It has provided detailed molecular insight into the extravascular leukocyte population during cardiopulmonary bypass. Although aprotinin blocked cardiopulmonary bypass-dependent extravasation of leukocytes, there was no change in their CD11b/CD62L activation status. The cantharidin skin test thus represents a novel research tool for evaluating future anti-inflammatory interventions in cardiothoracic surgery.

Finding a liability-free space in which personalized medicine can bloom

Personalized medicine uses genetic and other screening tests to predict a patient's response to specific drug and biologic therapies (together "drugs"), with the aim of choosing a treatment that will provide benefits while avoiding drug-related harms. There are two schools of thought on how tort liability may affect personalized medicine, i.e., whether fear of lawsuits will tend to accelerate progress or slow it down. Tort suits include product liability suits against manufacturers and negligence suits against physicians and other providers of health-related services.

Distinguishing Product and Practice Regulation in Personalized Medicine

Protecting the public from faulty targeting of medicines, while preserving the crucial distinction between product and practice regulation, may require innovative regulatory approaches and close, ongoing involvement by the medical profession. This article explores four problem areas: validation of clinical claims for tests used in targeting therapies; developing and implementing appropriate restrictions on off-label use; promoting consistent concepts of clinical utility for use in various regulatory, reimbursement, and judicial contexts; and communication of clear information to guide clinicians in appropriate use of targeted therapeutic products. The article suggests an approach for addressing these problems by sharing regulatory activities between the Food and Drug Administration and a newly-created clinical standards board formed within the medical and scientific communities.

Hemoglobin Scavenger Receptor CD163 Mediates Interleukin-10 Release and Heme Oxygenase-1 Synthesis

The recently described hemoglobin scavenger receptor CD163 mediates the endocytosis of hemoglobin:haptoglobin (Hb:Hp) complexes and thereby counters Hb-induced oxidative tissue damage after hemolysis. Although CD163 has been indirectly associated with antiinflammatory and atheroprotective activity, no ligand-receptor-effector pathway has yet been described for this receptor. To understand the significance of CD163 and more clearly define downstream pathways linked to inflammatory resolution, we studied the expression and function of CD163 in human monocytes/macrophages using both in vitro and in vivo models. Differentiation of human blood monocytes into macrophages either by in vitro culture or in resolving cantharidin-induced skin blisters led to an equivalent increase (>15x) in CD163 expression. Elevated CD163 levels were also noted on circulating monocytes in cardiac surgical patients during the resolution phase of the systemic inflammatory response to cardiopulmonary bypass surgery. In each case, binding of Hb:Hp to CD163-bearing cells elicited potent interleukin-10 secretion, and this was inhibited by the anti-CD163 antibody RM3/1. Release of interleukin-10, in turn, induced heme oxygenase-1 stress protein synthesis via an autocrine mechanism. Such induction of heme oxygenase-1 was observed in vivo 24 to 48 hours after the onset of cardiopulmonary bypass surgery. These results identify novel antiinflammatory and cytoprotective effector pathways in human monocytes/macrophages related to Hb scavenging and metabolism, which may have relevance in atheroprotection, wound healing, and patient recovery postoperatively.

Hybridization and population genetics of two macaque species in Sulawesi, Indonesia

This study investigates hybridization and population genetics of two species of macaque monkey in Sulawesi, Indonesia, using molecular markers from mitochondrial, autosomal, and Y-chromosome DNA. Hybridization is the interbreeding of individuals from different parental taxa that are distinguishable by one or more heritable characteristics. Because hybridization can affect population structure of the parental taxa, it is an important consideration for conservation management. On the Indonesian island of Sulawesi an explosive diversification of macaques has occurred; seven of 19 species in the genus Macaca live on this island. The contact zone of the subjects of this study, M. maura and M. tonkeana, is located at the base of the southwestern peninsula of Sulawesi. Land conversion in Sulawesi is occurring at an alarming pace; currently two species of Sulawesi macaque, one of which is M. maura, are classified as endangered species. Results of this study indicate that hybridization among M. maura and M. tonkeana has led to different distributions of molecular variation in mitochondrial DNA and nuclear DNA in the contact zone; mitochondrial DNA shows a sharp transition from M. maura to M. tonkeana haplotypes, but nuclear DNA from the parental taxa is homogenized in a narrow hybrid zone. Similarly, within M. maura divergent mitochondrial DNA haplotypes are geographically structured but population subdivision in the nuclear genome is low or absent. In M. tonkeana, mitochondrial DNA haplotypes are geographically structured and a high level of nuclear DNA population subdivision is present in this species. These results are largely consistent with a macaque behavioral paradigm of female philopatry and obligate male dispersal, suggest that introgression between M. maura and M. tonkeana is restricted to the hybrid zone, and delineate one conservation management unit in M. maura and at least two in M. tonkeana.

A review of the management of 323 consecutive patients seen in a specific learning difficulties clinic

Visual correlates of specific learning difficulties (SpLD) include: binocular instability, low amplitude of accommodation, and Meares-Irlen Syndrome. Meares-Irlen Syndrome describes asthenopia and perceptual distortions which are alleviated by using individually prescribed coloured filters. Data from 323 consecutive patients seen over a 15 month period in an optometric clinic specialising in SpLD are reviewed. Visual symptoms and headaches were common. 48% of patients were given a conventional optometric intervention (spectacles, orthoptic exercises) and 50% were issued with coloured filters, usually for a trial period. 40% of those who were given orthoptic exercises were later issued with coloured overlays. 32% of those who were issued with coloured overlays were ultimately prescribed Precision Tinted lenses. Approximately half the sample were telephoned more than a year after the last clinical appointment. More than 70% of those who were prescribed Precision Tints were still wearing them daily, and results for this intervention compared favourably with data for non-tinted spectacles. The data suggest that many people with SpLD need optometric care and that the optometrist needs to be skilled in orthoptic techniques and cognisant of recent research on coloured filters.

Randomised double-masked placebo-controlled trial of a treatment for congenital nystagmus

Several therapies have been developed for congenital nystagmus (CN) but without placebo-controlled trials. We investigated a treatment which combined two therapies that had been advocated by several authors and were reported to improve visual acuity (VA). A placebo treatment was designed to mimic the time, attention, 'high tech' apparatus, and the explanation used in the experimental treatment. To each group, 38 subjects with CN were randomly allocated. Their VA and contrast sensitivity (CS) were assessed three times before undergoing treatment for 6 weeks and then once more. An improvement in VA occurred, however, this was not significantly different in the two groups. The improvement in CS was greater in the experimental than in the control group, but the difference failed to reach significance in most statistical tests. We conclude that putative therapies for CN should be assumed to be placebos until proven otherwise with randomized controlled trials.

The current practice patterns of mechanical ventilation for respiratory failure in pediatric patients

OBJECTIVE

To quantify the current practice patterns of mechanical ventilation for respiratory failure in pediatric patients.

DESIGN

Mail survey using 2 hypothetical case studies sent to pediatric critical care physicians.

MEASUREMENTS AND MAIN RESULTS

The required arterial blood gas (ABG) on conventional mechanical ventilation (CMV) is pH = 7.25 to 7.29, PO2 = 50 to 59 torr, O2 saturation = 0.85 to 0.89. Most of our survey participants will treat a patient failing conventional mechanical ventilation in their pediatric intensive care units (PICUs) with inverse ratio ventilation (IRV) (95%) and with high-frequency oscillatory ventilation (HFOV) (92%).

CONCLUSION

Most of the surveyed pediatric critical care physicians practice permissive hypercapnia in the treatment of their patients who receive ventilatory assistance. More than 90% of surveyed pediatric critical care physicians are presently using inverse ratio ventilation and high-frequency oscillatory ventilation. These data suggest that these innovative modes of therapy are already accepted as part of the standard therapeutic spectrum by the surveyed group of physicians.

The underachieving child

Visual factors in specific learning difficulties (SpLD) are reviewed. People with SpLD fail to achieve at a level that is commensurate with their intelligence. The commonest SpLD is dyslexia, which usually results from phonological processing/decoding deficits. Additionally, there are several optometric correlates of SpLD which may, in some cases, contribute to the learning difficulty. These correlates include binocular instability and a low amplitude of accommodation. Some people with reading difficulties and perceptual distortions/eyestrain can be helped by individually prescribed coloured filters. A visual processing anomaly is also often present in the form of a deficit of the transient visual system. The role of the optometrist is discussed.

Comparative molecular phylogeography of two Xenopus species, X. gilli and X. laevis, in the south-western Cape Province, South Africa

Xenopus gilli is a vulnerable anuran with a patchy distribution along the south-western coast of the Cape Province, South Africa. This species is sympatric with Xenopus laevis laevis, a widespread relative found over much of southern Africa. We examined the molecular phylogeography and population structure of the contact zone between these species to obtain information about historical biogeography and conservation management of this region. Analyses of the distribution, frequency, and cladistic and phenetic relationships among mitochondrial DNA haplotypes indicate that population subdivision is present in both taxa but that long-term isolation of sets of populations has occurred in X. gilli only. Haplotype and nucleotide diversity are also considerably higher within and among X. gilli ponds than X. l. laevis ponds in this region. We attribute the genetic segregation of X. gilli populations to ancient habitat fragmentation by ocean transgression into X. gilli habitat and to continued habitat alteration by human activity. The lower level of genetic diversity in X. L. laevis in this region is likely a result of a recent arrival of this taxon to the south-western Cape region relative to X. gilli. Population structure in X. l. laevis may be a result of isolation by distance. Clear evidence exists for at least two management units within X. gilli and strongly supports the establishment of protective measures east of False Bay in order to conserve a substantial portion of this species' extant genetic diversity.

Standardization of pyridinium crosslinks, pyridinoline and deoxypyridinoline, for use as biochemical markers of collagen degradation

The collagen crosslinks, pyridinoline and deoxypyridinoline, have been developed as urinary markers of bone resorption but, despite wide clinical application of the technique, comparatively little attention has been paid to the standardization of these compounds. In this study, pyridinoline and deoxypyridinoline have been purified from bone and converted completely to monochloride trihydrochloride salts. In addition to mass spectrometry and NMR spectroscopy, the purity of the isolated materials was assessed by microelemental analysis including the chloride counterions. These purified compounds were used to establish individual molar absorptivity values as primary standardization criteria for the two crosslinks. For pyridinoline in 0.1 mol/L HCl, epsilon at 295 nm was 5490 L mol(-1) cm(-1); in 50 mmol/L sodium phosphate, pH 7.5, epsilon at 325 nm was 5785. The corresponding values for deoxypyridinoline at acid and neutral pH were 5160 and 5290 L mol(-1) cm(-1). The availability of standardization criteria for the crosslinks will allow more meaningful comparisons of clinical data between different laboratories.

Standardization of pyridinium crosslinks, pyridinoline and deoxypyridinoline, for use as biochemical markers of collagen degradation

The collagen crosslinks, pyridinoline and deoxypyridinoline, have been developed as urinary markers of bone resorption but, despite wide clinical application of the technique, comparatively little attention has been paid to the standardization of these compounds. In this study, pyridinoline and deoxypyridinoline have been purified from bone and converted completely to monochloride trihydrochloride salts. In addition to mass spectrometry and NMR spectroscopy, the purity of the isolated materials was assessed by microelemental analysis including the chloride counterions. These purified compounds were used to establish individual molar absorptivity values as primary standardization criteria for the two crosslinks. For pyridinoline in 0.1 mol/L HCl, epsilon at 295 nm was 5490 L mol(-1) cm(-1); in 50 mmol/L sodium phosphate, pH 7.5, epsilon at 325 nm was 5785. The corresponding values for deoxypyridinoline at acid and neutral pH were 5160 and 5290 L mol(-1) cm(-1). The availability of standardization criteria for the crosslinks will allow more meaningful comparisons of clinical data between different laboratories.

Monoclonal antibody assay for free urinary pyridinium cross-links

The pyridinium cross-links of collagen, pyridinoline (Pyd) and deoxypyridinoline (Dpd), provide structural integrity and rigidity to collagen fibrils in bone. During bone degradation (resorption), the cross-links are released into the circulation and eventually excreted in urine. Pyridinium cross-link measurements in urine have been shown to be sensitive and specific indicators of resorption by both established HPLC and newer enzyme immunoassay (EIA) techniques. We have developed a monoclonal antibody that preferentially binds to the non-peptide-bound free forms of Pyd & Dpd. We have incorporated the antibody conjugated to alkaline phosphatase in a competitive EIA by using Pyd-coated microtiter strip wells. After a 3-h incubation of sample and antibody-enzyme conjugate, color is developed for 1 h with p-nitrophenyl phosphate as the substrate. The intraassay (n = 52) CVs were 3.0-7.6%, and interassay (n = 8) CVs were 6.1-7.4%. Comparisons of the assay (y) with HPLC (x) and a polyclonal antibody-based EIA (x') gave regression equations of y = 0.46x + 4, r = 0.96, and y = 0.56x' + 8, r = 0.96. The EIA detected increased Pyd & Dpd concentrations in urine from postmenopausal women and patients with osteoporosis, hyperthyroidism, hyperparathyroidism, and Paget disease of bone. EIA concentrations also reflected the reduction in Pyd&Dpd excretion resulting from estrogen replacement in surgically menopausal women. Measurement of pyridinium cross-links with this simple EIA appears to provide an accurate index of the rate of resorption and may be useful for metabolic bone disease assessment and monitoring the effects of antiresorptive therapy.

Monoclonal antibody assay for free urinary pyridinium cross-links

The pyridinium cross-links of collagen, pyridinoline (Pyd) and deoxypyridinoline (Dpd), provide structural integrity and rigidity to collagen fibrils in bone. During bone degradation (resorption), the cross-links are released into the circulation and eventually excreted in urine. Pyridinium cross-link measurements in urine have been shown to be sensitive and specific indicators of resorption by both established HPLC and newer enzyme immunoassay (EIA) techniques. We have developed a monoclonal antibody that preferentially binds to the non-peptide-bound free forms of Pyd & Dpd. We have incorporated the antibody conjugated to alkaline phosphatase in a competitive EIA by using Pyd-coated microtiter strip wells. After a 3-h incubation of sample and antibody-enzyme conjugate, color is developed for 1 h with p-nitrophenyl phosphate as the substrate. The intraassay (n = 52) CVs were 3.0-7.6%, and interassay (n = 8) CVs were 6.1-7.4%. Comparisons of the assay (y) with HPLC (x) and a polyclonal antibody-based EIA (x') gave regression equations of y = 0.46x + 4, r = 0.96, and y = 0.56x' + 8, r = 0.96. The EIA detected increased Pyd & Dpd concentrations in urine from postmenopausal women and patients with osteoporosis, hyperthyroidism, hyperparathyroidism, and Paget disease of bone. EIA concentrations also reflected the reduction in Pyd&Dpd excretion resulting from estrogen replacement in surgically menopausal women. Measurement of pyridinium cross-links with this simple EIA appears to provide an accurate index of the rate of resorption and may be useful for metabolic bone disease assessment and monitoring the effects of antiresorptive therapy.

A preliminary investigation into the aetiology of Meares-Irlen syndrome

A recent double-masked placebo-controlled trial has confirmed that some children experience a reduction in symptoms of eyestrain and headache when they read through individually prescribed coloured filters and has shown that this benefit cannot be solely attributed to a placebo effect. People who are helped by coloured filters in this way have been described as having "Meares-Irlen syndrome'. We investigated the mechanism of this benefit by studying the optometric and visual perceptual characteristics of the children in the double-masked study. This population had normal refractive errors and heterophorias (none of the subjects had strabismus). They demonstrated slightly, but significantly, reduced amplitudes of accommodation and vergence and poor stereo-acuity. However, these factors seemed to be correlates of Meares-Irlen syndrome rather than the underlying cause. Pattern glare, a sensitivity to striped patterns (e.g. lines of text), was prevalent in our sample and was significantly associated with the subjects' symptoms. The spatial contrast sensitivity function was normal.

New technique for studying incision depth in experimental radial keratotomy

Older techniques of analyzing incision depth in incisional keratotomy consist of serial transverse sections taken at various points along the incision. Information as to shape and depth of the incision are reconstructed from these sections. We describe a new method for studying the incision depth and profile along the entire incision length.

Coronary operations in patients with spinal cord injury

BACKGROUND

The risk of heart disease in patients with spinal cord injury is similar to that in the general population. The physiologic derangements raise special problems in patients with SCI having coronary operations.

METHODS

From January 1980 to May 1995, we performed coronary artery bypass procedures on 20 patients with SCI; 4 were tetraplegic and the remainder were paraplegic. The indication for operation was angina: unstable (13), exertional (4), or postinfarctional (3). Bowel and bladder care was given immediately before operation; operating room tables were double padded and a pelvic wrap was used to protect the back. Electric wheelchairs were used for early mobilization.

RESULTS

Vasomotor instability from cardiopulmonary bypass was not present in patients with SCI. Pharmacologic support was required in the operating room by 4 patients for low vascular resistance, but in only one case in the intensive care unit. One patient required ventilation support for more than 24 hours. All patients were able to cough effectively. No thoracic wound complications occurred. There were three operative deaths, all in patients with multiple risk factors. The acute hospital stay averaged 9.3 days; patients were then transferred to an SCI unit for rehabilitation, were upper-extremity weight bearing was restricted for 2 to 4 weeks.

CONCLUSIONS

Patients should not be denied coronary artery bypass procedures because of an SCI, but their special needs must be managed properly.

Consulting skills training and medical students' interviewing efficiency

In more traditional medical education, medical students took a patient's medical history by asking a series of sequenced, routine questions, covering presenting medical problem(s); medical history; social and personal history; systems review; and physical examination. Following this process, the student then attempted to derive the patient's medical problems. This inductive problem-solving paradigm may not assist students to prepare for their future interviewing needs, given doctors use a hypothetico-deductive, problem-solving approach when interviewing patients and numerous researchers have developed specialized communication skills training programmes designed to enhance students' interviewing skills. Students given specific consulting skills training have tended to show significantly greater interpersonal effectiveness and improved interview behaviours compared with students who experience traditional patient clerking training. These improvements in interviewing tend to persist over the period of students' medical training. The aim of the present study was to determine whether specialized communication skills training helped students elicit greater quantity and quality of information from patients and if so, whether such information assisted students in improving their diagnostic skills. Videotaped history-taking interviews conducted by students trained in communication skills and untrained (control) students were rated for their interview efficiency. A comparison of ratings given by experimentally naive, independent observers revealed that trained students were more efficient, but took no longer than their control group counterparts to elicit fuller, more relevant information. However, the student groups did not differ in the accuracy or scope of their medical diagnoses. It is argued that students' lack of medical knowledge in this early phase of their clinical training militated against their being able to use their interviewing competence to derive more potentially accurate medical diagnoses.

Dyslexia: the link with visual deficits

Some research reports suggest that visual anomalies may have a causative role in dyslexia, and on this basis certain forms of therapy have been proposed. Recently, we have published the initial results of a matched group study which found dyslexia to be associated with binocular instability, reduced amplitude of accommodation, and reduced contrast sensitivity for both low spatial frequencies and uniform field flicker. The binocular instability was best identified by measuring the vergence amplitude: a modified Dunlop test failed to differentiate reliably between the two groups. Here, we report a significant correlation between flicker threshold and binocular instability, thus linking sensory and motor visual correlates of dyslexia. We also present further new analyses on the interaction between optometric variables and the psychometric measurement of coding skills. The results of these analyses disagree with a recent claim that binocular vision anomalies might cause poor performance at coding tasks. Our studies indicate that visual characteristics are not the major aetiological factors in specific reading difficulty.

Optometric correlates of Meares-Irlen syndrome: a matched group study

People who report visual perceptual distortions, typically when reading, that are alleviated by using coloured filters are described as suffering from 'Meares-Irlen Syndrome'. A recent double-masked placebo-controlled trial showed that this condition cannot be solely explained as a placebo effect and that the beneficial filter is idiosyncratic and sometimes needs to be highly specific. Several mechanisms have been suggested for Meares-Irlen Syndrome including ocular motor (binocular and accommodative) anomalies, a sensitivity to patterned stimuli (pattern glare), and a deficit of the transient visual sub-system. We investigated these hypotheses by comparing 16 children, who reported the symptoms described above and who showed a sustained benefit from coloured filters, with 25 control children who came from the same school and were matched for age, reading performance and intelligence. The 'Meares-Irlen Syndrome' group had slightly, but significantly, reduced vergence and accommodative amplitudes and stereo-acuity; they also demonstrated significantly more pattern glare. The two groups did not differ significantly in their visual acuities, refractive error, dissociated or associated heterophoria, AC/A ratio, or ability to perceive 20 Hz flicker. It appears that certain ocular motor factors are correlates of Meares-Irlen Syndrome, rather than the primary underlying cause of the symptoms. The results support the hypothesis that pattern glare may be involved in the mechanism of Meares-Irlen Syndrome.

A new protocol for the optometric management of patients with reading difficulties

Research by Evans et al. (Ophthal. Physiol. Opt. 15, 481-487, 1995) has demonstrated a correlation between visual processing and ocular motor factors in people with specific reading difficulties (dyslexia). In addition, research by Wilkins et al. (Ophthal. Physiol. Opt. 14, 365-370, 1994) has shown that some people with dyslexia will benefit from a reduction of perceptual symptoms of discomfort and distortion if they use individually prescribed coloured filters. Three examples of the dyslexic patients who attend at the Institute of Optometry clearly demonstrate the importance of full investigation of ocular function, including the assessment of the effect of colour on visual perception. All three patients presented with similar symptoms of asthenopia when reading. Symptoms were alleviated for the first patient by use of orthoptic treatment of an exotropia with intermittent suppression. With the second patient, ocular motor functions were found to be within acceptable limits and relief of symptoms was obtained by the prescribing of lenses of a specific chromaticity. For the third patient, both orthoptic intervention and the use of specifically tinted lenses were necessary to relieve the visual difficulties that were being experienced. By taking advantage of recent research and developments in optometric instrumentation, it is possible for some of those with dyslexia to receive considerable benefit from optometric intervention.

Is there a visual deficit in dyslexia resulting from a lesion of the right posterior parietal lobe?

Dyslexia has conventionally been attributed to a left hemisphere deficit affecting language skills. However, it has recently been suggested that two-thirds of dyslexic people have a lesion of the right posterior parietal lobe (RPPL) resulting in poor oculo-motor control. It has been reported that neurological patients with RPPL lesions commonly manifest a neglect of the left side of space and this has also been described in clinical observations of 'visual dyslexics'. We investigated this hypothesis with a sample of 53 dyslexic children and 53 controls using a line-bisection task. In the horizontal test condition both groups tended to transect slightly to the left of the midpoint (mean displacement 0.14 mm for controls; 0.4 mm for dyslexics). The result suggests a small right side neglect which, contrary to one report in the literature, is found here in developmental dyslexics as well as controls, and leads to the conclusion that RPPL lesion is unlikely to be a common feature of dyslexia.

Effect of pattern glare and colored overlays on a stimulated-reading task in dyslexics and normal readers

Scotopic sensitivity syndrome or the Irlen syndrome describes symptoms of asthenopia anamolous visual performance experienced while reading that are lessened by colored filters. One putative explantation for this condition relates to pattern glare: a hypersensitivity to repetitive patterns, including lines of print on a page. Experiment 1 used a placebo-controlled paradigm to investigate the effect of pattern glare and colored overlays on performance at a simulated reading visual search task. Despite the fact that the subjects were university students, the results showed a tendency, of border-line significance, to support the conclusion that colored filters seem to improve reading through ameliorating pattern glare. In experiment 2 we compared the prevalence of pattern glare in matched groups of dyslexic children and good readers. The dyslexic group reported more pattern glare, but also reported more glare from a control stimulus. Pattern glare in the dyslexic group was directly correlated with flicker sensitivity. The results are related to recent research on visual processing and ocular-motor function in dyslexia.

Double-masked placebo-controlled trial of precision spectral filters in children who use coloured overlays

We selected 68 children who reported benefit from individually chosen sheets of coloured plastic placed upon the page when reading, and who used these regularly without prompting. These children viewed text illuminated by coloured light in an apparatus that allowed the separate manipulation of hue (colour) and saturation (depth of colour), at constant luminance. Many of the children reported improvements in perception when the light had a chromaticity within a limited range, which was different for each individual. A pair of plastic spectacle lenses ('experimental' lenses) was dyed so as to provide the appropriate chromaticity under conventional white (F3) fluorescent light. An additional pair was prepared having very similar colour but with a chromaticity outside the range in which perception was reported to improve ('control' lenses). Each pair was provided for 1 month in random order. The children kept diaries (36 completed) recording symptoms of eye-strain and headache. The children and those responsible for their assessment were unable reliably to distinguish 'experimental' from 'control' lenses. Nevertheless, symptoms were less frequent on days when the 'experimental' lenses were worn (P < 0.003).

Videokeratographic evaluation of peripheral redeepening in the cadaver eye

Radial incisions must be deep enough to correct myopia. As currently performed, most surgeons set their diamond blades at a constant depth and do not alter the blade length throughout the procedure. The cornea is not uniformly thick; the central cornea is the thinnest and it thickens toward the periphery. Therefore, an incision of constant depth would be deeper centrally and thinner peripherally. Peripheral redeepening of the cornea would in theory make the incision depth deeper throughout and should increase the effect of radial incisions. We reviewed the literature on this technique and performed radial incisional studies on the human cadaver eye using videokeratography to measure incision depth indirectly. Based on our studies, we believe that peripheral redeepening has no effect on central cornea flattening.

An investigation of some sensory and refractive visual factors in dyslexia

The role of visual factors in dyslexia has been a long-standing source of controversy. Recent research has suggested that there may be a deficit of the transient visual subsystem in dyslexia. The evidence for this hypothesis comes principally from investigations of spatial and temporal contrast sensitivity and visual persistence. This evidence is reviewed and it is noted that previous work has never applied two of these purported "tests of transient function" to the same subject group. The hypothesised transient system deficit in dyslexia was investigated in a study comparing 43 control with 39 dyslexic children who were matched for age, sex, and intelligence. Comprehensive psychometric and optometric data were obtained, including visual acuities and refractive errors. The spatial contrast sensitivity function was determined in such a way as to investigate further the findings of Lovegrove, Martin, Bowling, Blackwood, Badcock and Paxton [(1982) Neuropsychology, 20, 309-315] and Martin and Lovegrove [(1984) Neuropsychologia, 22, 73-77]. It might be expected, from the work of Merigan and Maunsell [(1990) Neuroscience, 5, 347-352], that a better test of magno-cellular function would be to investigate the modulation threshold for a virtually uniform field that was flickering sinusoidally at 10 Hz. This temporal contrast sensitivity was studied in a similar way to Brannan and Williams [(1988) Clinical Vision Sciences, 3, 137-142]. A non-verbal simulated reading visual search task was used to investigate the effect of any visual deficits on a test that was, in its low-level visual requirements, similar to reading. The following factors were found to be significantly associated with dyslexia: reduced visual acuity, impaired flicker detection at 10 Hz, reduced low spatial frequency contrast sensitivity, and slightly slower performance at a simulated reading visual search task. The two alleged "tests of transient function" were only weakly correlated with one another (r = 0.183), suggesting that these variables do not measure the same function. Much of the dyslexic group's slightly slower performance at the simulated reading task could be accounted for by the psychometric variable of visual sequential memory. Like reading, the simulated reading task requires the accurate perception of sequential characters. Hence, it seems unlikely that the low-level visual deficits in the dyslexic group were major causes of their poor reading performance. Alternative explanations for the results are discussed.

Functional characteristics of small placental arteries

OBJECTIVES

The aim of this study was to investigate characteristics of placental arteries capable of influencing vasomotor tone in the fetoplacental vascular bed. Contractile characteristics and endothelium-dependent and endothelium-independent relaxation were examined.

STUDY DESIGN

By means of a small vessel myograph arteries of mean normalized internal diameter 353.22 +/- 13.14 microns were studied under isometric conditions. Contractile function was assessed with a variety of agonists, including angiotensin II, endothelin-1, the thromboxane mimetic U46619, prostaglandin E2, and prostaglandin F2 alpha. The effect of physiologic and supraphysiologic PO2 on vascular function was also examined. Relaxation was assessed in response to known endothelium-dependent vasodilators, including acetylcholine, bradykinin, histamine, and A23187 and to sodium nitroprusside (endothelium independent). The effect of indomethacin and the nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl ester on contractile function was also evaluated.

RESULTS

Sensitivity to sodium nitroprusside was reduced by a high PO2. U46619 was the most potent constrictor agonist studied. The response of precontracted arteries to known endothelium-dependent vasodilators was minimal, other than for histamine, which led to modest relaxation. The constrictor response to U46619 was increased in the presence of NG-nitro-L-arginine methyl ester.

CONCLUSIONS

Oxygen tension may be an important determinant of relaxation in small placental arteries. Receptor-mediated release of endothelium-derived relaxing factor is not a major mechanism in the fetoplacental circulation.

Investigation of accommodative and binocular function in dyslexia

The visual correlates of dyslexia are the subject of controversy, and much evidence suggests that they may include some aspects of binocular and accommodative function. These factors were investigated in 43 control and 39 dyslexic children, who were matched for age, sex and performance intelligence quotient. The dyslexic group exhibited significantly lower positive and negative vergence reserves, and vergence instability when the eyes were dissociated at near. Their amplitudes of accommodation also were significantly reduced. However, other measures including dissociated and associated heterophoria and accommodative lag and facility were similar in both groups. The stability of motor ocular dominance, as assessed with a modified Dunlop test, was similar in both groups. The results of a simulated reading visual search task suggested that the vergence and accommodative dysfunction were not a major cause of the dyslexia. Further analyses, using reading-age matched groups, suggested that these ocular motor correlates were not attributable to the better reading performance in the control group. The most likely remaining explanation is that they are, in most cases, non-causal correlates of the dyslexia.

Behavioural assessment of the effectiveness of a communication programme for medical students

This study evaluated the effectiveness of a communication programme taught to medical students at the University of Melbourne in their preclinical years. The effectiveness of the programme was assessed by comparing videotaped history-taking interviews completed by a cohort of first-year clinical students in 1986, who had not undertaken the communication programme, with a similar cohort of first-year clinical students in 1992 who had undertaken the programme. The students from the 1986 cohort who had not undertaken communication training in their preclinical course completed their videotaped interviews as part of the experimental evaluation of a consulting skills training programme carried out in 1986-87. A comparison of ratings given by two experimentally naive, independent observers revealed that the 1992 student cohort demonstrated some significantly better skills at questioning and facilitating communication with patients. By contrast, the 1986 student cohort showed significantly greater skills at maintaining relevance in their interviews and greater capacity to explore patients' psychosocial concerns. These data suggest that students acquire the most effective interview skills when interacting with patients during their clinical training.

Measuring medical students' empathy skills

Empathy is an important skill for the medical practitioner or medical students to develop when interviewing patients. It helps the interviewer establish effective communication, which is important for accurate diagnosis and patient management. Two facets of medical education limit students' development of accurate empathy: the traditional format of interviewing training and the social ethos of medical training and medical practice, which stress clinical detachment. A number of researchers and educators have developed consulting skills training programmes, designed to enhance students' empathic skills and ability. One difficulty for researchers has been the conceptual complexity of the term 'empathy' and greater difficulty in measuring the dimension. This paper reviews the range of approaches to the measurement of empathy and reports on a research study designed to evaluate a two-stage measurement technique, involving a pencil-and-paper test of empathy and independent observer ratings of medical students' actual interview behaviours. Results lead to the conclusion that pencil-and-paper tests of empathy cannot incorporate the range of complex cognitive, emotional and behavioural components of the empathy construct. On the other hand, trained observers have been able to use items on a specially developed History-taking Rating Scale to discriminate between the empathic behaviours of a group of students trained in consulting skills with those of a group of control students who each carried out videotaped history-taking interviews with hospitalized patients.