Rich and abundant spider communities result from enhanced web capture breadth and reduced overlap in urban greenspaces

Urbanization is a key contributor to biodiversity loss, but evidence is mounting that cities can support rich arthropod communities, including rare and threatened species. Furthermore, greenspace is growing within hundreds of "shrinking cities" that have lost population resulting in a need to demolish an overabundance of infrastructure creating vacant land. Efforts are underway to transform vacant lots, often viewed as blighted areas, into habitats that promote biodiversity and generate ecosystem services, such as urban agroecosystems. To understand how reconfiguring these greenspaces might influence species conservation, elucidation of the factors that drive the distribution of an urban species pool is needed. In particular, the importance of species interactions in structuring urban communities is poorly understood. We tested hypotheses that (1) greater breadth of prey captured by web-building spiders and reduced overlap of prey capture among individuals facilitates the conservation of genera richness and abundance and (2) heterogeneity within a greenspace patch facilitates enhanced dietary niche breadth and greater resource partitioning. In 2013 and 2014, the abundance, breadth and degree of overlap in prey capture of sheet web spiders (Linyphiidae) was measured using web mimic traps at 160 microsites (0.25 m² ) situated in four urban vacant lots and four urban farms in the city of Cleveland, Ohio, USA. Within a subset of 40 microsites, we used vacuum sampling and hand collection to measure the abundance and genera richness of Linyphiidae. Spider richness and abundance were significantly reduced within urban farms relative to vacant lots. The distribution of spiders and prey was explained by habitat structure, with microsites dominated by tall grasses and flowering plants, with a high bloom abundance and richness, supporting greater prey capture and a higher genera richness and abundance of spiders. In 2014, web capture overlap was significantly greater within microsites dominated by bare ground. These findings illustrate that urban greenspace conservation efforts that focus on reducing bare ground and incorporating a diversity of grasses and flowering plant species can promote linyphiid spiders, potentially by relaxing exploitative competition for shared prey.

Migration histories of multidrug-resistant tuberculosis patients from the Thailand-Myanmar border, 2012-2014

SETTING

Multidrug-resistant tuberculosis (MDR-TB) is a growing public health threat in South-East Asia. TB is typically a disease of poverty and can be spread by infectious humans who migrate from one region to another.

DESIGN

We interviewed 20 MDR-TB patients on the Thailand-Myanmar border with regard to their migration histories. Migration origins and destinations were mapped.

RESULTS

All but one participant had a history of migration, and maps of migration ranges revealed wide geographic dispersal. Most described living and work conditions that could contribute to the spread of drug-resistant TB, including numerous contacts and crowded living quarters.

CONCLUSION

Our results show that at least some migrant workers in the region carry MDR-TB, and indicate that this subgroup of the population is important with regard to the transmission of MDR-TB throughout the region. Migrants in this region come into contact with high numbers of people and may be able to spread the disease across wide geographic ranges. Access to diagnosis and treatment and socio-economic development are at least as important as any TB control measures, meaning that innovative and bold approaches that extend across international borders are needed to address these problems.

Active dispersal in loggerhead sea turtles (Caretta caretta) during the 'lost years'

Highly migratory marine species can travel long distances and across entire ocean basins to reach foraging and breeding grounds, yet gaps persist in our knowledge of oceanic dispersal and habitat use. This is especially true for sea turtles, whose complex life history and lengthy pelagic stage present unique conservation challenges. Few studies have explored how these young at-sea turtles navigate their environment, but advancements in satellite technology and numerical models have shown that active and passive movements are used in relation to open ocean features. Here, we provide the first study, to the best of our knowledge, to simultaneously combine a high-resolution physical forcing ocean circulation model with long-term multi-year tracking data of young, trans-oceanic North Pacific loggerhead sea turtles during their 'lost years' at sea. From 2010 to 2014, we compare simulated trajectories of passive transport with empirical data of 1-3 year old turtles released off Japan (29.7-37.5 straight carapace length cm). After several years, the at-sea distribution of simulated current-driven trajectories significantly differed from that of the observed turtle tracks. These results underscore current theories on active dispersal by young oceanic-stage sea turtles and give further weight to hypotheses of juvenile foraging strategies for this species. Such information can also provide critical geographical information for spatially explicit conservation approaches to this endangered population.

Tick communities at the expanding wildlife/cattle interface in the Eastern Cape Province, South Africa: implications for Corridor disease

Corridor disease, transmitted by the brown ear tick (Rhipicephalus appendiculatus), is one of Africa's most pathogenic tick-borne diseases for cattle. With a focus on this species, we investigated the community parameters (richness, diversity and abundance) of ticks in the Eastern Cape, South Africa, and how this may be linked to the increasing wildlife/cattle interface in the region. There were significantly more ticks of a greater diversity and richness at sites positioned at the wildlife/cattle interface ('treatment sites') compared to sites where wildlife was absent (controls). Significantly, R. appendiculatus was only found at the treatment sites. Therefore, it is believed that the wildlife/cattle interface may be playing a crucial role in increasing the occurrence, abundance and distribution of R. appendiculatus in the Eastern Cape. The implications of a Corridor disease outbreak in the region are discussed.

Erosion of enamel by non-carbonated soft drinks with and without toothbrushing abrasion

OBJECTIVE

To investigate how enamel loss due to erosion, and due to cycling of erosion and abrasion, depends on compositional parameters of soft drinks, and particularly whether the thickness of the erosive softened layer is a function of drink composition.

SETTING

University dental hospital research laboratory in the UK, 2004.

MATERIALS AND METHODS

Six drinks were chosen based on their popularity and composition: apple juice, orange juice, apple drink, orange drink, cranberry drink and 'ToothKind' blackcurrant drink. Group A samples (n = 36) were exposed to soft drinks at 36 degrees C for six consecutive 10 minute periods. Group B samples (n = 36) were subjected to alternating erosion and toothbrushing, repeated six times. Enamel loss was measured using optical profilometry.

RESULTS

Group A: significant enamel loss was seen for all drinks (p < 0.001). Erosion was correlated with pH and calcium concentration but not phosphate concentration or titratable acidity. Group B: significant additional material loss due to toothbrush abrasion occurred with all drinks. Abrasive enamel loss differed between the drinks and was positively correlated with drink erosive potential.

CONCLUSION

Enamel loss by erosion is exacerbated by subsequent abrasion. The amount of softened enamel removed by toothbrushing is a function of the chemical composition of the erosive medium.

The relationship between enamel softening and erosion caused by soft drinks at a range of temperatures

OBJECTIVES

Investigations of the erosive potential of soft drinks are usually performed at room or body temperature, but drinks are more frequently served chilled, with ice, or hot. Since the rate of chemical reactions usually increases with temperature, it is predicted that erosion is more severe at high temperatures and reduced at low temperatures. The aim of this study was to investigate the correlation between enamel softening, enamel erosion, and temperature.

METHODS

Atomic force microscopy nanoindentation and non-contact optical profilometry were used to assess changes in enamel nanomechanical properties after 5 min and erosive material loss after 30 min exposure to two different non-carbonated soft drinks at 4, 25, 50 and 75 degrees C.

RESULTS

For one drink (Robinson's Original Juice Drink), there was a statistically significant difference between nanomechanical properties and erosion depth at all temperatures, with softening and erosion increasing with temperature. For another drink (Ribena ToothKind Juice Drink), there was a slight softening and virtually no material loss, and temperature had no statistically significant impact on erosion. There was a good linear correlation (R2 = 0.94) between nanomechanical properties and material loss.

CONCLUSIONS

The difference between the drinks can be explained by their composition. For the erosive drink, material loss increased, and nanohardness decreased, approximately linearly with temperature. The correlation between softening and erosion demonstrated that nanomechanical properties after very short erosion times can be considered a good predictor of bulk material loss after considerably longer erosion times.

Relationship between enamel erosion and liquid flow rate

The association of severe erosion with certain habits of consuming soft drinks prompted a study of erosion in relation to fluid flow. In the main experiments, citric acid solution (pH 3.2) was directed at polished enamel surfaces at flow rates of 26, 67 or 126 ml min(-1) through outlets of diameters 1.0, 2.6 or 5.0 mm for up to 20 min. Erosion depth increased with time of exposure and total volume of solution, with increasing flow rate and with decreasing outlet diameter. Scanning electron microscopy of acid-treated surfaces and of the subsurface enamel indicated that the clearance of dissolution products, rather than the mechanical dislodgement of partly dissolved crystal bundles, was the main process involved. For an exposure time of 20 min, erosion increased with (liquid velocity)(1/4). In a secondary experiment, it was found that the erosive potential of a low-erosive drink did not increase with increasing liquid velocity. The rapid increase in the rate of erosion caused by citric acid at low liquid velocities shows that reproducible stirring is essential for precision and intercomparison of in vitro studies. It also accounts for the rapid erosion seen when erosive drinks are consumed from a straw placed labial to the anterior teeth, or are "swished" between the teeth.

Sensitivity of Venturia inaequalis Populations to Anilinopyrimidine Fungicides and Their Contribution to Scab Management in New York

Sensitivities of Venturia inaequalis isolates to the anilinopyrimidine fungicides (APs) pyrimethanil and cyprodinil were determined for nine populations by measuring the growth of colonies formed from germinating conidia derived from single scab lesions. At the discriminatory pyrimethanil dose of 0.2 μg ml^-1, the mean relative growth range measured for eight V. inaequalis populations (n = 39 to 74) never treated with AP fungicides varied from 18.1 to 48.2, translating into an approximately sixfold difference in mean baseline sensitivities. For the composite of all 469 isolates tested, sensitivities to pyrimethanil and to the sterol demethylation inhibitor (DMI) myclobutanil were significantly correlated. When isolates were organized into subpopulations based on their sensitivities to an individual fungicide, sensitivities to both fungicides declined in parallel through the highly and moderately sensitive spectra of subpopulations, but they diverged for isolates in subpopulations least sensitive to either fungicide. The result suggested that at least one of the multiple genes conferring DMI resistance also lowered the sensitivity to AP fungicides. The relative contribution of AP fungicides to scab management was evaluated at an experimental orchard representative of the Great Lakes region of the United States. Frequencies of DMI-resistant isolates of V. inaequalis had progressed to the stage of practical resistance at the site, and the sensitivity to pyrimethanil was similar to several commercial orchard populations never treated with APs. For management programs at the experimental site involving the AP fungicides cyprodinil and pyrimethanil and conducted from 1996 to 2000, the level of fruit and terminal leaf scab control was inferior to that of nonspecific protectants such as mancozeb or captan. For the control of scab on cluster leaves, the efficacy of AP fungicides equaled the performance of nonspecific protectants. This modest contribution of AP fungicides to scab management might have been caused by a lack of the extended cool temperature conditions that were conducive to AP performance in northern Europe in previous studies, and/or by the reduced sensitivity to AP fungicides in this DMI-resistant V. inaequalis population.

Human enamel erosion in constant composition citric acid solutions as a function of degree of saturation with respect to hydroxyapatite

The objective of this study was to investigate human enamel erosion under constant composition conditions, as a function of solution degree of saturation (DS) with respect to hydroxyapatite. The experimental conditions were relevant to the initial stages of enamel erosion by soft drinks. Nanoindentation was used to compare enamel surface softening caused by a control mineral water and two citric acid solutions with DS = 0.000 and DS = 0.032, both having pH 3.30. Enamel hardness and reduced elastic modulus were measured after 0, 30, 60, 120, 300 and 600 s exposure. A statistically significant change in enamel hardness was detected after 30 s exposure to both citric acid solutions, indicating that nanoindentation is extremely sensitive to the initial stages of erosion. There was a statistically significant difference between the mechanical properties of enamel exposed to the two citric acid solutions after 30, 60 and 120 s. At these times, the solution with DS = 0.000 caused twice as much enamel softening as that with DS = 0.032. This demonstrates that it may be possible to design a soft drink with a low erosive potential and a good taste by a small change in DS, at a typical drink pH.

A comparison of enamel erosion by a new sports drink compared to two proprietary products: a controlled, crossover study in situ

OBJECTIVE

The aim of the study was to measure the erosive potential of a prototype sports drink on enamel in a model in situ.

METHODS

The study was a single centre, single blind, randomised crossover design balanced for residual effects involving 18 subjects. The drinks were the prototype formulation containing calcium and maltodextrin (test), two sports drink products containing sugars (drink with calcium and positive control) and water (negative control). During each 15-day study period, subjects wore a palatal removable appliance carrying two flat human enamel specimens. Drinks were imbibed as 250 ml volumes over 10 min 4 times per day. Loss of enamel was measured on days 5, 10 and 15 using a contacting profilometer.

RESULTS

Very little erosion occurred with the test, drink with calcium and negative control drinks and differences between the test and negative control only reached significance at day 15. The positive control produced progressive erosion over time and significantly more than the test or negative control at all time points.

CONCLUSION

The technology of adding calcium with appropriate pH adjustment, which has been applied previously to soft and carbonated drinks to markedly reduce erosive potential, can be applied to sports drinks to the same end. Significant variation in the carbohydrate composition does not influence this outcome.

Toothbrush Abrasion of Surface Softened Enamel Studied with Tapping Mode AFM and AFM Nanoindentation

The aim of the present in vitro study was to investigate the toothbrush abrasion of surface softened enamel using tapping mode atomic force microscopy (TM-AFM) and AFM nanoindentation. TM-AFM investigations showed that the typical prismatic pattern as observed after demineralisation was retained after toothbrushing. The exposure to artificial saliva resulted in the deposition of a 'sausage-shape' material with random orientation. Brushing of these samples did not lead to a complete removal of this deposited material. Enamel mineral loss increased with increasing demineralisation time and increased further, although only to a small extent, due to subsequent toothbrushing. Exposure to artificial saliva did not alter the amount of enamel mineral lost due to the brushing treatment. AFM nanoindentation investigations showed that the three different demineralisation treatments caused three statistically different reductions in both surface hardness and reduced elastic modulus values, with the shortest exposure time having the least effect on the nanomechanical properties of the enamel samples. Toothbrushing did result only in a small increase in hardness and reduced elastic modulus. The present study has shown that toothbrushing of surface softened enamel leads to minor changes in the surface morphology and nanomechanical properties. The amount of enamel lost due to toothbrushing was independent of the demineralisation time and was lower compared to the mineral loss caused by the demineralisation treatments. Furthermore, the exposure to artificial saliva offers minimal protective effect to the softened enamel surface against toothbrushing.

A Two-Phase Resistance Response of Venturia inaequalis Populations to the QoI Fungicides Kresoxim-Methyl and Trifloxystrobin

The class of fungicides acting as respiration inhibitors by binding to the Qo center of cyto-chrome b (QoIs) are in wide use for the management of apple scab caused by Venturia inaequalis. In order to assess responses of V. inaequalis populations to treatments with QoIs, sensitivities of isolates were determined for germinating conidia or for mycelial colonies developing from germinating conidia. Under both test conditions, inhibitory potencies of kresoxim-methyl and trifloxystrobin were largely equivalent. V. inaequalis populations treated with QoIs in a commercial and an experimental orchard both responded with significant shifts toward declining QoI sensitivities. However, the population responses were quantitative in nature, and highly resistant isolates indicative of a cytochrome b target site mutation were not detected. V. inaequalis populations from both orchards investigated also were fully resistant to sterol de-methylation-inhibiting fungicides (DMIs) such as fenarimol and myclobutanil, but isolate sensitivities to QoIs and DMIs were largely unrelated. Performance tests with kresoxim-methyl and trifloxystrobin at the experimental orchard diagnosed as DMI-resistant revealed that the quantitative shift toward declining QoI sensitivities did not constitute the status of practical QoI resistance. In contrast to these quantitative responses, emergence of qualitative QoI resistance was documented for V. inaequalis in an orchard in North Germany, which had been treated intensively with a total of 25 QoI applications over four consecutive seasons. Isolates retrieved from the orchard were highly resistant to both kresoxim-methyl and trifloxystrobin and were characterized as G143A cytochrome b mutants. The results indicated that the paths of QoI resistance can be both quantitative and qualitative in nature. A similar phenomenon has not been described before. Circumstantial evidence suggests that the quantitative phase of V. inaequalis population responses to QoIs might be succeeded by a quantitative selection of highly resistant G143A target-site mutants.

Development of low erosive carbonated fruit drinks 2. Evaluation of an experimental carbonated blackcurrant drink compared to a conventional carbonated drink

OBJECTIVE

Previous studies demonstrated that a non-carbonated blackcurrant juice drink with added calcium produced little erosion of enamel in vitro and in situ by comparison with other low pH fruit drinks. The aim of this study is to evaluate the erosive effects in situ of an experimental formulation carbonated drink with added calcium, compared to a conventional carbonated drink over a 20 day period using a similar design as in previous studies.

METHOD

The study was a single centre, single blind, randomised placebo controlled three cell crossover design involving 15 volunteers. The test drinks were an experimental carbonated ready-to-drink (RTD) blackcurrant drink, a conventional carbonated RTD orange drink and water. Two enamel samples were retained in situ, in the midline of the hard palate on an upper removable acrylic appliance. Drinks were 250 ml volumes consumed four times per day during 20 working days. Measurements of enamel loss were made on enamel samples after days 2, 5, 10, 15 and 20 by profilometry.

RESULTS

The experimental carbonated blackcurrant drink caused significantly less enamel loss than the conventional carbonated orange drink at all time points measured, but was not significantly different from water at days 2, 5 and 20.

CONCLUSIONS

This study has shown that it is possible to modify carbonated soft drinks in a manner similarly shown with non-carbonated soft drinks, to minimise dental erosion.

Development of low erosive carbonated fruit drinks. 1. Evaluation of two experimental orange drinks in vitro and in situ

OBJECTIVES

To determine the in vitro erosive potential and in situ erosive effect of two new formulation low calorie carbonated orange drinks with that of two conventional diet products and water.

METHODS

In the in vitro study, six specimens of deciduous and permanent enamel were randomly allocated to each of the five products and a '4h' protocol employed. In the in situ study, 15 healthy volunteers participated in a single centre, single blind, 5-phase crossover study, conducted according to Good Clinical Practice, and employing a validated model.

RESULTS

The in vitro erosive potential of the experimental formulations was less than that of the comparators at all time points. Conversely, the observed erosive potential of both experimental formulations was greater than that of the control. Consistent statistically significant differences were found in relation to permanent enamel only. Unfortunately, the in situ study did not produce results entirely consistent with those of the in vitro study. Notably, a generally progressive loss of enamel was observed in specimens exposed to the control.

CONCLUSIONS

The data from the in vitro study show the experimental formulations to have low comparative erosivity. However, the methodologies in vitro and in situ somewhat unusually do not correlate in ranking the erosivity of drinks. The results of this study should therefore be viewed with caution, further research being clearly warranted.

The Early Stages of Native Enamel Dissolution Studied with Atomic Force Microscopy

Food-induced demineralization (erosion) is one of the key factors in surface structural changes of tooth enamel, with soft drinks being a significant etiological agent. The objective of this study was to measure early stages of enamel loss with high accuracy on native enamel surfaces combined with qualitative observations of changes in the surface morphology using the atomic force microscope (AFM). Native unerupted third molar surfaces were partly covered with a gold reference layer. Samples were imaged with the AFM before dissolution (at baseline) and after exposure to three different drinks (mineral water, a "toothkind" blackcurrant drink, and a lemon and lime juice drink) at five different exposure times (15 min, 30 min, 1 h, 2 h, and 3 h). The changes in the surface morphology were investigated qualitatively as well as quantitatively. This study showed that the maximum material loss occurred at the aprismatic parts of the enamel close to the perikymata. The maximum enamel loss was greatest for the lemon and lime juice drink and lowest for water. A two-way ANOVA of the transformed data, employing the natural logarithm, showed a statistically significant difference between both the drinks and the exposure time at a 95% confidence level (P=0.000). This demonstrates that the AFM is a suitable tool for measuring early stages of enamel demineralization. Copyright 2000 Academic Press.

Effects of pH and concentration of citric, malic and lactic acids on enamel, in vitro

OBJECTIVE

Dental erosion associated with soft drink consumption probably results from the contained dietary acids in the formulations. The pH value of any formulation is an important variable in acid erosion but not necessarily the only important factor. The aim of this study was to measure enamel erosion by citric, malic and lactic acids at pH values and acid concentrations representative of a range found in soft drink formulations and to determine the effect of adding calcium to citric acid.

METHODS

Flat ground enamel samples were prepared from unerupted human third molar teeth. Groups of five specimens were placed in citric, malic and lactic acid solutions of different pH and acid concentration for three by 10 min exposures at 35 degrees C. Enamel loss was measured by profilometry. Enamel specimens were also exposed to citric acid solutions containing calcium at different pH values and at the same pH with different concentrations of calcium.

RESULTS

Numerical data and contour plots for each acid showed a similar pattern for increasing erosion with decreasing pH and increasing acid concentration and vice versa for decreasing erosion. Increasing the concentration of calcium in a fixed pH citric acid solution resulted in decreased erosion. This effect was most marked at higher pH.

CONCLUSIONS

This study has shown that under highly controlled conditions the erosion of enamel by solutions of dietary acids is influenced by the interplay of pH, acid concentration and presence of calcium. These variables and in particular the concentration of calcium could be manipulated to produce soft drinks with reduced erosivity to enamel.

Development and evaluation of a low erosive blackcurrant juice drink. 2. Comparison with a conventional blackcurrant juice drink and orange juice

OBJECTIVE

A previous study demonstrated that an experimental low pH blackcurrant juice drink with calcium was markedly less erosive to enamel both in situ and in vitro than orange juice. Further development of the experimental blackcurrant juice drink formula has occurred and the aims of the present studies were two fold. Firstly, to confirm the low erosivity of the modified formulation and secondly, to provide more comparative data with other acidic fruit drink products.

METHOD

The study was a single centre, single blind, randomised placebo controlled 4 cell crossover design involving 12 healthy volunteers. The test drinks were orange juice, water, experimental blackcurrant juice drink with calcium and a proprietary blackcurrant juice drink. Enamel samples were retained in situ at the mid palatal regions using intraoral appliances and exposed to 250 ml volumes of the drinks 4 times per day during 15 working days. Measurements of enamel loss were made by profilometry. The same method was modelled in vitro.

RESULTS

By day 15 the mean losses of enamel in situ for orange juice, water, experimental blackcurrant juice drink with calcium and blackcurrant juice drink were 1.70, 0.05, 0.44 and 2.75 microns respectively. At all bar one measurement, the loss of enamel was significantly greater for all fruit drinks compared to water. Losses caused by the blackcurrant juice drink with calcium were significantly less than the other two fruit drinks at all time points. Losses of enamel by day 15 in the study in vitro were 13.02, 0.00, 1.78 and 39.02 microns respectively. The blackcurrant juice drink with calcium was not significantly different from water at days 3 and 6, otherwise all pairwise comparisons for differences between the 4 drinks at each time period were significant.

CONCLUSIONS

The methodologies in situ and in vitro again appear to correlate in ranking the order of erosivity of drinks. The data particularly from the study in situ allude to the very low comparative erosivity of the further modified experimental blackcurrant juice drink with calcium and support the further development of such drinks for public consumption.

Development and evaluation of a low erosive blackcurrant juice drink. 3. Final drink and concentrate, formulae comparisons in situ and overview of the concept

OBJECTIVE

Two previous studies demonstrated that a blackcurrant juice drink with added calcium produced little erosion of enamel in vitro and in situ by comparison with other low pH fruit drinks. The primary aim of this study was to demonstrate that the final formulation drink and concentrate were of similar low erosivity. Secondary aims were to provide more data on the erosivity of other fruit drink concentrates and whether erosion was influenced by anterior and posterior palate siting of enamel specimens.

METHOD

The study was a single centre, single blind, randomised placebo controlled 5 cell crossover design involving 15 volunteers. The test drinks were blackcurrant juice/calcium concentrate, blackcurrant juice/calcium drink, proprietary apple & blackcurrant juice concentrate, proprietary orange drink concentrate and water. Four enamel samples were retained in situ, 2 anterior palate and 2 mid/posterior palate, on upper removable acrylic appliances. Drinks were 250 ml volumes consumed 4 times per day during 15 working days. Concentrates were diluted 50 ml in 200 ml water. Measurements of enamel loss were made on one anterior and one posterior sample on days 2, 5, 10 and 15 by profilometry.

RESULTS

One subject approached the 20 microns erosion limit by day 10 on the orange drink and was withdrawn from that cell. Differences in mean erosion between anterior and posterior sites were variable and small. By day 15 the mean losses of enamel averaged over anterior and posterior were blackcurrant/calcium concentrate 0.28 micron, blackcurrant/calcium drink 0.35 micron, apple & blackcurrant concentrate 2.04 microns. orange concentrate 8.29 microns and water 0.08 micron. Except at day 15 for the blackcurrant/calcium drink the erosion by the blackcurrant/calcium formulations was not significantly different from water at any time point. Erosion by the apple & blackcurrant and orange concentrate drinks was highly significantly greater than the blackcurrant/calcium drinks at all but the 2 day time point for the apple & blackcurrant concentrate drink compared to the blackcurrant/calcium drink.

CONCLUSIONS

All data thus far indicate that dependant on tooth site susceptibility and the specific drink, the consumption of standard low pH fruit drinks could result in 1 mm loss of enamel in periods ranging from as little as 2 years to 20 years. Similar erosion by the low pH blackcurrant drinks with added calcium would take in excess of 100 years.

Development and evaluation of a low erosive blackcurrant juice drink in vitro and in situ. 1. Comparison with orange juice

OBJECTIVE

The aim of this study was to determine whether an experimental blackcurrant juice drink with added calcium was less erosive to enamel both in vitro and in situ compared with a proprietary orange juice product.

METHODS

The study was a single centre, blind, randomised, placebo controlled three cell crossover design. An intra oral appliance capable of retaining one enamel sample in situ was constructed and worn by 12 volunteers. The drinks under test were orange juice, the experimental blackcurrant juice drink with calcium and water. Drinks were consumed as 250 ml volumes four times during the working day under supervision for 15 days. The same methodology was modelled in vitro. Measurements of enamel loss were made by profilometry.

RESULTS

Water, the experimental blackcurrant juice drink and orange juice produced 0.19, 0.41 and 2.54 microns loss of enamel respectively in situ and 0.0, 5.2 and 22.18 microns loss of enamel respectively in vitro. All differences between pairs of drinks in situ and in vitro were statistically significant.

CONCLUSIONS

Data using this model in situ were only available for orange juice and this was therefore considered as a positive control with water a placebo control. The results have demonstrated that the experimental blackcurrant juice drink with calcium is markedly less erosive than orange juice, particularly and importantly in situ. The experimental blackcurrant juice drink has limited erosive potential to teeth and deserves further comparative investigation and development as a low pH fruit drink for public consumption.

A method to measure clinical erosion: the effect of orange juice consumption on erosion of enamel

OBJECTIVE

Acidic soft drinks are frequently implicated in dental erosion, but there are limited supporting data. Research is problematic due to the insidious nature of erosion and accuracy in assessing tissue loss. The aim of this study was to develop and validate, using a negative control, a model to accurately measure erosion in situ due to a single aetiological agent over a relatively short time period.

METHODS

An intra-oral appliance capable of retaining an enamel sample was designed in order to assess the effect of orange juice consumption on enamel. The study was a single centre, randomized, placebo controlled, blind, crossover design.

RESULTS

Ten subjects, each consuming 11 of orange juice per day for 15 days, showed significantly more erosion on the enamel specimens than the same subjects consuming 11 of water per day over the same time period, measurements undertaken with surfometry. The same investigation was performed in vitro. Again, orange juice was significantly more erosive; indeed, it was in the order of 10 times that produced in situ. Surface microhardness testing in situ and in vitro demonstrated statistically significant differences between exposed and unexposed areas after orange juice treatment.

CONCLUSIONS

Changes produced by water either in situ or in vitro were always well within the baseline measurement parameters (+/- 0.3 micron) set down for the method and hence validated the clinical model in terms of reproducibility and accuracy in measurement. It is concluded that this method has confirmed the erosive potential of orange juice in situ. The method could have many applications to study dental erosion under highly controlled conditions and over realistic time periods.

Evidence for the view that temporospatial integration in vision is temporally anisotropic

In two experiments low-pass and high-pass spatially filtered versions of a base image were prepared and the effect of the order of delivery of sequences of filtered and base images investigated. A task that required subjects to discriminate 120 ms presentations of a full-bandwidth base image and degraded sequences that contained sets of three different spatially filtered versions, or mixtures of spatially filtered and full-bandwidth versions of the image, were used. Each set of images used in the degraded sequences was presented either so that within the 120 ms presentation window the spatial content swept from low to high spatial frequencies or from high to low. In experiment 1 twenty subjects discriminated between a base image and degraded sequences of an urban scene. Results showed both a significant overall effect of image order, with low-to-high spatial-frequency information delivery being mistaken more often for the full-bandwidth presentation than high-to-low, and that different sets of degraded image sequences varied significantly in the frequency with which they were mistaken for the full-bandwidth presentation. In experiment 2 a base and filtered versions of a human face were used in an identical task with twenty different subjects and a very similar pattern of significant results was obtained, although imposed on a lower overall error frequency than that obtained in experiment 1. It was concluded that the results of both experiments provide evidence for an anisotropic temporospatial integration mechanism in which availability of spatial information in a low-to-high spatial-frequency sequence results in more efficient integration than a high-to-low.

Role of coarse and fine spatial information in face and object processing

In 4 experiments the role of coarse (low-pass filtered) and fine (high-pass filtered) spatial information in guiding visual processing was studied in a same-different task. The second of a pair of sequential patterns was either a normal image or the first 100 ms was restricted either coarse or fine information before a normal image was shown for the rest of the presentation. This 100-ms cue could be from the immediately succeeding image (relevant) or from other images in the set (irrelevant). Analysis of response times and errors showed relevant coarse- and fine-scale cues were usually equally effective, but any differences favored fine-scale versions. Irrelevant fine-scale cuing was significantly more disruptive than coarse-scale cuing. No evidence of preferential cuing by coarse-scale information occurred in any experiment.

Role of coarse and fine spatial information in face and object processing

In 4 experiments the role of coarse (low-pass filtered) and fine (high-pass filtered) spatial information in guiding visual processing was studied in a same-different task. The second of a pair of sequential patterns was either a normal image or the first 100 ms was restricted either coarse or fine information before a normal image was shown for the rest of the presentation. This 100-ms cue could be from the immediately succeeding image (relevant) or from other images in the set (irrelevant). Analysis of response times and errors showed relevant coarse- and fine-scale cues were usually equally effective, but any differences favored fine-scale versions. Irrelevant fine-scale cuing was significantly more disruptive than coarse-scale cuing. No evidence of preferential cuing by coarse-scale information occurred in any experiment.

Effects of high-pass and low-pass spatial filtering on face identification

If face images are degraded by block averaging, there is a nonlinear decline in recognition accuracy as block size increases, suggesting that identification requires a critical minimum range of object spatial frequencies. The identification of faces was measured with equivalent Fourier low-pass filtering and block averaging preserving the same information and with high-pass transformations. In Experiment 1, accuracy declined and response time increased in a significant nonlinear manner in all cases as the spatial-frequency range was reduced. However, it did so at a faster rate for the quantized and high-passed images. A second experiment controlled for the differences in the contrast of the high-pass faces and found a reduced but significant and nonlinear decline in performance as the spatial-frequency range was reduced. These data suggest that face identification is preferentially supported by a band of spatial frequencies of approximately 8-16 cycles per face; contrast or line-based explanations were found to be inadequate. The data are discussed in terms of current models of face identification.

The depiction of distance: a Bartelian analysis

Work by Bartel has shown that observers make systematic errors when attempting to set a receding row of staves at equal intervals, and make even-more-pronounced errors in the same direction when drawing a similar row; consequently, the factors that contribute to this systematic distortion in spatial representation were examined. The results indicate that the tendency to overestimate nearer distances and underestimate further distances in pictorial space may be enhanced both by increasing the size ratio of the nearest and furthest pictorial elements and by increasing the angle of convergence of represented parallel contours. However, it is clear that size ratio is the more powerful independent variable. The reasons for this discrepancy are discussed and an explanation of the pattern of pictorial distortion, in terms of a compromise between an objective representation of the relative estimated distance of the depicted distances and an inaccurately anticipated optical projection, is proffered.

Viewing angle and the perceived orientation of pictorial elements: geometric or representational effects?

The role of geometric shape properties in determining the perceived orientation (heading) change of picture elements was investigated in four experiments. In experiment 1 the systematic change in perceived heading of each of a depicted team of horses which projected irregular geometric shapes was measured. In experiment 2, involving silhouettes, the perceptual axes of these same horse shapes, together with those of a pair of enantiomorphic deltoid shapes, were derived. These derived shape axes were used in experiment 3, along with single oblique contours, to determine the degree of heading shift as a function of the complexity and orientation of the shape. The degree of heading shift was remarkably similar for both silhouette shapes and the single contours when the axes were oblique but, whereas vertical orientation was predicted to abolish heading shift, this was only true for the deltoid shapes. In experiment 4 a possible explanation of the nonpredicted heading shift for the vertically oriented horse silhouettes was investigated. Subjects' individual estimates of the axes of the horse shapes, rather than a group mean value, were used to set the horse shapes to the vertical. When viewing was from two positions no significant heading change with view was found. Taken as a whole the data suggest that the geometric properties of patterns, rather than their representative nature, determine the very obvious heading shift when pictures are viewed from different angles.

TNF-alpha induces peroxynitrite-mediated depletion of lung endothelial glutathione via protein kinase C

We tested the hypothesis that tumor necrosis factor-alpha (TNF) induces a peroxynitrite (ONOO-)-mediated depletion of glutathione via a protein kinase C (PKC)-dependent mechanism in pulmonary artery endothelial monolayers (PAEM). PAEM were incubated with TNF (1,000 U/ml) for 6 and 18 h. The PAEM were assayed for ONOO(-)-dependent changes in the concentration of luminol, free glutathione [Gfree; i.e., reduced glutathione and oxidized glutathione (GSSG)] and GSSG. TNF treatment decreased luminol and Gfree, and increased GSSG and GSSG/Gfree, compared with treatment with control media. The TNF-induced effects were prevented by co-incubation with the nitric oxide synthase inhibitors NG-monomethyl-L-arginine (1 mM), NG-nitro-L-arginine methyl ester (1 mM), or NG-nitro-L-arginine (1 mM). In addition, the TNF-induced effects were prevented by superoxide dismutase (10 U/ml), which removes O2-, and by urate (0.5 mM) and L-cysteine (3 mM), putative scavengers of ONOO-. The treatment of PAEM with the PKC activator phorbol 12-myristate 13-acetate (PMA, 1 microM) induced similar alterations in luminol and glutathione as TNF. TNF and PMA induced a protein of similar molecular weight (approximately 90 kDa) in the focal contact-rich fraction of PAEM lysate. TNF- and PMA-induced effects were prevented with the specific PKC inhibitor calphostin C (1 microM). The data indicate that TNF-induced PKC activation mediates ONOO- generation, which results in the oxidation and depletion of glutathione in PAEM.

Spatial content and spatial quantisation effects in face recognition

It has recently become apparent that if face images are degraded by spatial quantisation, or block averaging, there is a nonlinear acceleration of the decline in accuracy of recognition as block size increases. This suggests recognition requires a critical minimum range of object spatial frequencies. Two experiments were performed to clarify the phenomenon. In experiment 1, the speed and accuracy of recognition for six frontoparallel photographs of faces were measured. After familiarisation training sessions, the images were shown for 100 ms with 11, 21, and 42 pixels per face, horizontally measured. Transformations calculated to remove the same range of spatial frequencies were performed by means of quantisation, a Fourier low-pass filter, and Gaussian blurring. Although accuracy declined and speed increased in a significant, nonlinear manner in all cases as the image quality was reduced, it did so at a faster rate for the quantised images. In experiment 2, faces rated as being typical were shown at 9, 12, 23, and 45 pixels per face and with appropriate Fourier low-pass versions. The nonlinear decline was confirmed and it was shown that it could not be attributed to a ceiling effect. A further condition allowed quantised and Fourier low-pass conditions to be compared with an unstructured-noise condition of equal strength to that of the quantised images. These gave comparable, but slightly less impaired, recognition than the quantised images. It can be inferred from these results that the removal of a critical range of at least 8-16 cycles per face of information explains the step decline in recognition seen with quantised images. However, the decline found with quantised images is reinforced by internal masking from pixelisation.

The perception of spatial structure with oblique viewing: an explanation for Byzantine perspective?

Earlier work has confirmed that (i) observers can judge divergent receding lines, placed directly in front of them, to be parallel, and (ii) converging lines which are displaced laterally, so that they are viewed obliquely, can also be judged to be parallel. The former observation is in accord with traditional views of perspective while the latter, which is in accord with the depictions of objects found in Byzantine painting, is not in accord with perspective but is predicted by the relative magnitude of the visual angles subtended by the near and far ends of the pair of lines. To investigate whether these effects occurred when the stimulus was clearly three-dimensional, experiments were conducted with a novel apparatus, consisting of a framework of computer-controlled motor-driven luminous rods. This could be remotely adjusted so that all visible sides appeared to be parallel, ie to resemble a cube. Results showed that observers set the sides of this trapezohedron framework as diverging when it was viewed immediately in front of them, a result which is concordant with linear perspective, ie they see the normal projection of a cube as having converging edges. When the framework was displaced from the median plane so that it was viewed obliquely, the sides were set as converging and the magnitude of this effect was significantly related to angle of view, ie observers see the normal projection of a cube as having diverging sides.(ABSTRACT TRUNCATED AT 250 WORDS)

Tumor necrosis factor-alpha activates pulmonary artery endothelial protein kinase C

We investigated the hypothesis that tumor necrosis factor-alpha (TNF) activates pulmonary endothelial protein kinase C (PKC). Confluent bovine pulmonary artery endothelial monolayers were exposed to recombinant human TNF, and the translocation of PKC, an indicator of enzyme activation, was studied using both slot immunoblotting and immunofluorescence. For slot immunoblot analysis, membrane and cytosol lysate fractions were prepared, and PKC antigen was assessed using MC5 monoclonal anti-PKC antibody. TNF (1,000 U/ml for 15 min) induced translocation of PKC into the membrane. Immunofluorescence analysis with the MC5 antibody was also used. Monolayers treated with culture medium showed diffuse cytoplasmic fluorescence. In contrast, treatment with either TNF (1,000 U/ml for 15 min) or 1,2-dioctanoylglycerol (4 x 10(-5) M for 5 min), a diacylglycerol that activates PKC, resulted in translocation of fluorescence to the cell periphery; fine, punctate PKC-associated fluorescence was localized to the margins of cells. The TNF-induced translocation of PKC was inhibited using either IP-300 polyclonal anti-TNF antibody (indicating that the TNF effect was not due to the vehicle or contaminating endotoxin) or calphostin C (10(-6) M for 15 min), which inhibits PKC activation by interacting with the regulatory diacylglycerol-binding domain. TNF treatment had no effect on either the content of PKC, or of total protein, in the membrane + cytosol, and cycloheximide (40 microM for 5 min) did not alter the translocation of PKC induced by TNF; these results indicate that the effect of TNF on PKC translocation was related to neither de novo membrane synthesis of PKC (as opposed to translocation per se) nor nonspecific augmentation of protein synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Convergent and divergent perspective

Use of divergent (or inverse) perspective in pictures is often regarded as arbitrary or even as erroneous in spite of the fact that entire schools of art exist in which this kind of perspective is regularly used. An experiment is reported which shows that a significant trend towards divergent perspective is experienced by subjects viewing laterally displaced three-dimensional arrays. Centrally viewed arrays show the expected perceptual convergence. It is therefore argued that divergent perspective, under appropriate conditions, is as perceptually legitimate an experience as convergent perspective.

Apparent duration and spatial structure

In three experiments, we investigated the relative perceived duration of a full bandwidth image and a set of high- and lowpass filtered images of a scene, briefly presented on a visual display unit. In Experiment 1, the various images were compared with each other, using a paired comparison method. All images were presented for 40 msec, and observers were asked to judge which of each pair of images had the longest duration. The results showed that images containing a wide spatial frequency bandwidth were judged to be of longer duration than were images of a narrower bandwidth, regardless of whether the latter were high- or lowpass filtered. In Experiment 2, a 40-msec presentation of each of the images was compared with a presentation of a probe that was 20, 40, 60, or 80 msec in duration. Observers again judged which of each pair of images had the longest duration. The results were very similar to those of Experiment 1, with wide bandwidth images being judged to be of longer duration than were narrow bandwidth images. In Experiment 3, instead of comparing the various filtered versions of the image with each other, we attempted to obtain a direct measure of perceived duration by comparing a flashing LED to a 40-msec flash of a subset of the images used in the previous experiments. The observers' task was to adjust the duration of the LED flash to match the perceived duration of each image.(ABSTRACT TRUNCATED AT 250 WORDS)

Three-space inference from two-space stimulation

Oblique contours sloping at 30 degrees with respect to the horizontal were presented alone, in combination to form chevrons, or with a vertical line to form arrowhead or Y patterns; they were projected onto a screen in the frontal parallel plane and viewed from positions that gave viewing angles of 90 degrees (normal to the screen's surface), 53 degrees, or 34 degrees. The perceived orientation of the contours, as assessed by a movable arm that the subjects set to be parallel to the obliques, changed monotonically as a function of viewing angle. The change was as great for single obliques as for combinations of obliques within the chevron, arrowhead, and Y patterns. The results of Experiment 1 were extended in Experiment 2, in which obliques at 30 degrees and 50 degrees with respect to the horizontal were presented singly or in combination as chevron patterns. It is argued that the results of both experiments indicate that single two-space oblique lines are immediately interpreted as lying in three-space and that the changes in perceived orientation are a consequence of this perceptual inference.

Temporal integration of spatially filtered visual images

Factors which govern the temporal integration of spatial information were examined in a group of five experiments. A series of high-pass and low-pass spatially filtered versions of a visual scene were generated. Observers' ratings of these filtered versions of the scene for perceived image quality indicated that quality was determined both by the bandwidth of spatial information and the presence of high-spatial-frequency edge information. When sequences of three different versions of the scene were presented over an interval of 120 ms the perceived quality of the resulting composite image was determined both from the ratings of the individual components of that sequence and from the order in which these components were presented. When the order of spatial information in a sequence moved from coarse to fine detail the perceived quality of the composite image was significantly better than when the order moved from fine to coarse. This evidence of a coarse-to-fine bias in pattern integration was further investigated with a detection paradigm. The pattern of errors once again indicated that temporal integration of spatial information was superior when a coarse-to-fine mode of information delivery was employed. Taken together the data indicate that the pattern-integration mechanism has an inherent order bias and does not accumulate spatial information so efficiently when the 'natural' coarse-to-fine order is violated.

Functional studies of a glutamate dehydrogenase with known three-dimensional structure: steady-state kinetics of the forward and reverse reactions catalysed by the NAD(+)-dependent glutamate dehydrogenase of Clostridium symbiosum

Steady-state kinetic properties of glutamate dehydrogenase from Clostridium symbiosum are reported. Rates with NADP(H) are over three hundred times lower than with NAD(H) under identical conditions. The 3-acetyl pyridine and 6-deamino adenine analogues of NAD+, on the other hand, are used almost as well as NAD+ itself. Amino acid specificity is very tight at both pH 7 and pH 9. The best alternative substrate of those tested, L-alpha-amino-gamma-nitraminobutyrate, gave only 0.5% of the rate seen with glutamate. With 400 microM NAD+ a 160-fold variation of the glutamate concentration gave a linear Eadie plot apart from slight inhibition at the highest concentrations. With 40 mM L-glutamate and varied [NAD+], the Eadie plot appeared linear between 1.6 microM and 60 microM and again between 60 microM and 2000 microM, but the slopes of the two lines differed by a factor of 8.4. This striking pattern is not attributable to impurities in the coenzyme or to changes in the state of aggregation of the enzyme. For the high concentration range (greater than 60 microM NAD+), the presence of all four linear terms in the reciprocal form of the initial rate equation indicates a sequential mechanism. Similar measurements made for APAD+ and dnNAD+ show no sign of non-linearity in the Eadie plot over the wide concentration ranges explored. In the reductive amination direction, with NADH as coenzyme, linear reciprocal plots were obtained for all three substrates. Systematic variation of concentrations led via primary, secondary and tertiary plots to all eight possible initial-rate parameters in a linear reciprocal initial-rate equation. Compulsory-order and enzyme-substitution mechanisms appear to be excluded, and a random route to the central complex seems the only possibility compatible with the results.

The Short NART: cross-validation, relationship to IQ and some practical considerations

Beardsall & Brayne (1990) have presented a method whereby the full-length National Adult Reading Test (NART) scores of subjects who are of below average reading ability can be predicted from performance on the first half of the test (termed the Short NART). The accuracy with which the Short NART predicted full-length NART scores was examined in a large cross-validation sample (N = 674). A subgroup of this sample (N = 142) was administered the WAIS. The results indicated that the Short NART was only moderately successful in predicting full-length NART scores. However, comparison of the accuracy with which the full-length NART and Short NART predicted WAIS IQs, revealed that the superiority of the former was very minimal. It is concluded that, despite some reservations regarding the Short NART's practical utility, it can be used with reasonable confidence in clinical practice to estimate premorbid IQ.

A synthesis of acylphosphonic acids and of 1-aminoalkylphosphonic acids: the action of pyruvate dehydrogenase and lactate dehydrogenase on acetylphosphonic acid

Acylphosphonic acids, R-CO-PO(OH)2, have been synthesized by the steps [formula: see text] of which the last is new and provides a mild method for de-esterifying acylphosphonic acids. Their reductive amination gives a simple way of making 1-aminoalkylphosphonic acids. Acetylphosphonic acid inhibited NAD+ reduction by pyruvate with the pyruvate dehydrogenases from Escherichia coli and Bacillus stearothermophilus. The inhibition was competitive with pyruvate, with Ki of 6 microM for the E. coli enzyme (pyruvate Km 0.5 mM) and one of 0.4 mM of the B. stearothermophilus enzyme (pyruvate Km 0.1 mM). Acetylphosphonate and its monomethyl ester are substates for pig heart lactate dehydrogenase, with Km values of 15 mM and 10 mM respectively (pyruvate Km 0.05 mM) and specificity constants one thousandth that for pyruvate.

Intermittent alexia

A case of intermittent alexia, sometimes accompanied by severe dysgraphia and sometimes by mild dysgraphia, which had a probable migrainous origin, is described. On some occasions the patient could write to dictation, although with many errors, while unable to read words or letters. On other occasions the patient's writing to dictation was seriously disordered in terms of content and the letters were produced clumsily. Reading of numbers, colour vision and colour naming were normal although impairments on right-left orientation and visual short term memory were present and a mild finger agnosia was apparent. Blood flow scans (SPECT) taken under normal and alexic conditions support the view that the disturbance had a vascular origin.

Assessing the validity of NART-estimated premorbid IQs in the individual case

The National Adult Reading Test (NART: Nelson, 1982) has become the standard means of estimating premorbid intelligence. The danger in using the NART for this purpose is that it yields an invalid estimate if a client's performance on the test has suffered impairment. In the present study a sample of 659 healthy subjects was used to build a regression equation for the prediction of NART scores from demographic variables (i.e. years of education, social class, age and sex). The multiple correlation between these demographic variables and the NART was .70 (p less than .0001). Comparing a client's obtained and predicted NART score will permit the clinician to assess objectively whether NART performance is impaired, and thus whether or not the NART will provide a valid estimate of premorbid intelligence.

Reaction time measures of feature saliency in schematic faces

Two separate paradigms utilizing measurements of reaction time were employed to study facial feature saliency in schematic line drawn faces. In the first paradigm the speed of response to the omission of different facial components was measured, and in the second, the speed of response to feature substitution was measured. In both paradigms the facial features were presented in a random temporal sequence in order to minimise preferential scanning strategies. The two separate paradigms reflected the feature hierarchy most commonly found in the literature, ie the outline and eyes are more salient than the nose and mouth in terms of both speed of processing and error rate. In a third study the feature substitution paradigm was used to investigate the effects of feature saliency on the perception of emotional faces. The results suggest a change in the eyes/mouth hierarchy so that the mouth becomes the most salient feature in the surprised, happy, and sad target faces. This reverse in hierarchy, however, was not evident with the angry target face. These results are discussed in terms of changes in the focus of 'attention' and/or changes in 'processing efficiency'.

Multimodal imaging in Alzheimer's disease. The relationship between MRI, SPECT, cognitive and pathological changes

Patients with a clinical diagnosis of Alzheimer's disease were studied using MRI, SPECT, and psychometric tests. Significant correlations between focal perfusion deficits and focal cognitive deficits were found. Significant correlations between regional relaxation time of white matter and psychometric tests of diffuse and focal categories were also found. Pathological examination confirmed Alzheimer's disease as the only diagnosis.

Survival of severe neuroleptic malignant syndrome in a 78-year-old man treated with dantrolene

The authors report a case of neuroleptic malignant syndrome in a 78-year-old man. The patient presented with a lack of contact with reality, hallucinations to which he was responding incoherently, and agitation and belligerence. He showed much improvement following treatment with dantrolene and was released to a nursing home 24 days after admission.

Magnetic resonance imaging in Alzheimer's disease, multi-infarct dementia, alcoholic dementia and Korsakoff's psychosis

Regional spin lattice relaxation times (T1) measured during nuclear magnetic resonance imaging of the brain were compared in patients with Alzheimer's disease, multi-infarct dementia, alcoholic dementia, Korsakoff's psychosis and control subjects. Regional differences were found between all patient groups compared with controls and within patient groups, with the exception of the comparison between Korsakoff's psychosis and alcoholic dementia. Correlations between regional T1 change and cognitive test scores were also found, with particular emphasis between visuospatial deficits and parietal T1. The possible role of T1 measures in the pathophysiology of these disorders is discussed.

Estimating premorbid IQ from demographic variables: regression equations derived from a UK sample

The purpose of the study reported here was to build regression equations for the estimation of premorbid IQ from demographic variables in a UK population. Subjects (n=151) free of neurological, psychiatric or sensory disability, were administered the Wechsler Adult Intelligence Scale (WAIS) and had their demographic details recorded (age, sex, occupation and education). WAIS Full Scale (FSIQ), Verbal (VIQ), and Performance IQ (PIQ) were regressed on the demographic variables. The regression equations generated by this procedure predicted 50, 50, and 30 percent of the variance in FSIQ, VIQ, and PIQ respectively. These equations should provide a convenient and useful supplement to psychometric estimates of premorbid IQ. Unlike psychometric estimates, demographic estimates are entirely independent of a patient's current cognitive status.