Discovery of Novel, Orally Bioavailable Pyrimidine Ether-Based Inhibitors of ELOVL1

In our efforts to identify novel small molecule inhibitors for the treatment of adrenoleukodystrophy (ALD), we conducted a high-throughput radiometric screen for inhibitors of elongation of very long chain fatty acid 1 (ELOVL1) enzyme. We developed a series of highly potent, central nervous system (CNS)-penetrant pyrimidine ether-based compounds with favorable pharmacokinetics culminating in compound 22. Compound 22 is a selective inhibitor of ELOVL1, reducing C26:0 VLCFA synthesis in ALD patient fibroblasts and lymphocytes in vitro. Compound 22 reduced C26:0 lysophosphatidyl choline (LPC), a subtype of VLCFA, in the blood of ATP binding cassette transporter D1 (ABCD1) KO mice, a murine model of ALD to near wild-type levels. Compound 22 is a low-molecular-weight, potent ELOVL1 inhibitor that may serve as a useful tool for exploring therapeutic approaches to the treatment of ALD.

Novel 2-Substituted 7-Azaindole and 7-Azaindazole Analogues as Potential Antiviral Agents for the Treatment of Influenza

JNJ-63623872 (2) is a first-in-class, orally bioavailable compound that offers significant potential for the treatment of pandemic and seasonal influenza. Early lead optimization efforts in our 7-azaindole series focused on 1,3-diaminocyclohexyl amide and urea substitutions on the pyrimidine-7-azaindole motif. In this work, we explored two strategies to eliminate observed aldehyde oxidase (AO)-mediated metabolism at the 2-position of these 7-azaindole analogues. Substitution at the 2-position of the azaindole ring generated somewhat less potent analogues, but reduced AO-mediated metabolism. Incorporation of a ring nitrogen generated 7-azaindazole analogues that were equipotent to the parent 2-H-7-azaindole, but surprisingly, did not appear to improve AO-mediated metabolism. Overall, we identified multiple 2-substituted 7-azaindole analogues with enhanced AO stability and we present data for one such compound (12) that demonstrate a favorable oral pharmacokinetic profile in rodents. These analogues have the potential to be further developed as anti-influenza agents for the treatment of influenza.

Perception of Slope and Distance in Photographs and in the Real World

We report a series of experiments in which spatial judgments of the real world were compared with equivalent judgments of photographs of the real-world scenes. In experiment 1, subjects judged the angle from the horizontal of natural slopes. Judgments of slope correlated with true slope (r=0.88) but judgments were in general overestimates. Equivalent judgments of slope in photographs again correlated with true slope (r=0.91) but judgments tended to be overestimates for small angles (6°) and underestimates for larger angles (up to 25°). In experiment 2 slope judgments were made under laboratory conditions rather than in the natural world. The slopes, which were viewed monocularly, varied from 5° – 45°, and were either plain, or textured, or included perspective information (a rectangle drawn on the surface) or had both texture and perspective. Judgments were overestimates, but the correlation with true slope was high (r=0.97). Slopes with either texture or perspective were judged more accurately than plain slopes, but combining texture and perspective information conferred no further benefit. Judgment of the angle of the same slopes in photographs produced similar results, but the degree of overestimation (closer to the vertical) was greater than for the real slopes. In experiment 3, subjects either judged the distance of landmarks ranging from 200 m to 5000 m from the observation point, or judged distance to the landmarks in photographs. In both cases subjects' judgments were well described by a power function with exponents close to one. Although there are large individual differences, subjects' judgments of slope and distance are accurate to a scale factor, and photographs yield similar judgments to real scenes.

Artificial cloud test confirms volcanic ash detection using infrared spectral imaging

Airborne volcanic ash particles are a known hazard to aviation. Currently, there are no means available to detect ash in flight as the particles are too fine (radii < 30 μm) for on-board radar detection and, even in good visibility, ash clouds are difficult or impossible to detect by eye. The economic cost and societal impact of the April/May 2010 Icelandic eruption of Eyjafjallajökull generated renewed interest in finding ways to identify airborne volcanic ash in order to keep airspace open and avoid aircraft groundings. We have designed and built a bi-spectral, fast-sampling, uncooled infrared camera device (AVOID) to examine its ability to detect volcanic ash from commercial jet aircraft at distances of more than 50 km ahead. Here we report results of an experiment conducted over the Atlantic Ocean, off the coast of France, confirming the ability of the device to detect and quantify volcanic ash in an artificial ash cloud created by dispersal of volcanic ash from a second aircraft. A third aircraft was used to measure the ash in situ using optical particle counters. The cloud was composed of very fine ash (mean radii ~10 μm) collected from Iceland immediately after the Eyjafjallajökull eruption and had a vertical thickness of ~200 m, a width of ~2 km and length of between 2 and 12 km. Concentrations of ~200 μg m⁻³ were identified by AVOID at distances from ~20 km to ~70 km. For the first time, airborne remote detection of volcanic ash has been successfully demonstrated from a long-range flight test aircraft.

Isosteric replacements of the carboxylic acid of drug candidate VX-787: Effect of charge on antiviral potency and kinase activity of azaindole-based influenza PB2 inhibitors

VX-787 is a first in class, orally bioavailable compound that offers unparalleled potential for the treatment of pandemic and seasonal influenza. As a part of our routine SAR exploration, carboxylic acid isosteres of VX-787 were prepared and tested against influenza A. It was found that the negative charge is important for maintaining potency and selectivity relative to kinase targets. Neutral carboxylic acid replacements generally resulted in compounds that were significantly less potent and less selective relative to the charged species.

The metabolic inter-relationships between changes in waist circumference, triglycerides, insulin sensitivity and small, dense low-density lipoprotein particles with acute weight loss in clinically obese children and adolescents

OBJECTIVE

Small, dense low-density lipoprotein (LDL) particles are highly atherogenic and strongly associated with obesity-related dyslipidemia. The metabolic inter-relationships between weight loss induced changes in waist circumference, triglycerides, insulin sensitivity and small-dense LDL particles in clinically obese children and adolescents have not been studied.

METHODS

Seventy-five clinically obese boys and girls (standardized body mass index 3.07 ± 0.59, aged 8-18 years) were recruited. Anthropometric, body composition and cardiometabolic risk factors were measured pre- and post-weight loss.

RESULTS

There were highly significant reductions in anthropometric, body composition and cardiometabolic risk factors. Triglyceride change was positively correlated with LDL peak particle density and percentage LDL pattern B changes (relative abundance of small, dense LDL particles). Multiple regression analyses showed that changes in triglyceride concentration accounted for between 24 and 18% of the variance in LDL peak particle density and percentage LDL pattern B change, respectively. Changes in waist circumference and insulin sensitivity did not predict these changes in LDL characteristics.

CONCLUSION

Acute and highly significant weight loss significantly decreased LDL peak particle density and percentage LDL pattern B. The change in triglycerides was a strong predictor of LDL peak particle density and percentage LDL pattern B change.

Impact of Schmallenberg virus on British sheep farms during the 2011/2012 lambing season

British sheep farmers were invited to complete a questionnaire about the impact of Schmallenberg virus (SBV) on animal health, welfare and their own emotional wellbeing during the 2011–2012 lambing season, through Defra and Farming Industry websites, letters to farmers who had requested SBV laboratory tests and advertisement at Sheep 2012. The 494 responders included SBV confirmed (positive by RT-PCR) (n=76), SBV suspected by farmer (n=140) or SBV not suspected (n=278). Percentage of barren ewes was similar across SBV groups, however, lamb and ewe losses were higher on responder farms where SBV was confirmed or suspected. The median percentages of all lambs born (and lambs born deformed ) that died within one week of birth was 10.4 per cent (5.5 per cent), 7.0 per cent (2.9 per cent) and 5.3 per cent (0 per cent), respectively, on SBV confirmed, suspected and not suspected farms (P<0.001). Eight to 16 per cent of SBV confirmed or suspected farms reported lamb mortality of ≥40 per cent. Farmer perceived impact was greater where SBV was confirmed or suspected (P<0.001): 25 per cent reported a high impact on emotional wellbeing (4 per cent of SBV not suspected), 13 per cent reported a high impact on flock welfare and financial performance and 6 per cent were less likely to farm sheep next year because of SBV (<2 per cent in SBV not suspected). Overall, SBV impact has been large relative to reported sheep loss.

Multiple somatic symptoms predict impaired health status in functional somatic syndromes

BACKGROUND

The relationship between functional somatic syndromes and multiple somatic symptoms is unclear.

PURPOSE

We assessed whether the number of somatic symptoms is a predictor of health status in three functional somatic syndromes (FSS).

METHODS

In a population-based study of 990 UK adults we assessed chronic widespread pain (CWP), chronic fatigue (CF) and irritable bowel syndrome (IBS) by questionnaire and medical record data. We assessed health status (Short Form 12 and EQ-5D), number of somatic symptoms (Somatic Symptom Inventory) and anxiety/depression (Hospital Anxiety and Depression Scale) both at baseline and at follow-up 1 year later.

RESULTS

The proportion of people with an FSS who also have multiple somatic symptoms (52-55 %) was similar in the three functional syndromes. The presence of multiple somatic symptoms was associated with more impaired health status both at baseline and at follow-up. This finding was not explained by severity of FSS. In the absence of multiple somatic symptoms, the health status of the FSS was fair or good. In multiple regression analysis, the number of somatic symptoms, the presence of a functional syndrome (CWP or CF) and anxiety/depression were predictors of EQ-5D thermometer at follow-up after adjustment for confounders.

CONCLUSIONS

Multiple somatic symptoms in people with an FSS are associated with impaired health status and this cannot be explained by more severe functional syndrome or the presence of anxiety and depression.

Wildfires, fuel treatment and risk mitigation in Australian eucalypt forests: insights from landscape-scale simulation

Wildfires pose significant risks to people and human infrastructure worldwide. The treatment of fuel in landscapes may alter these risks but the magnitude of this effect on risk is poorly understood. Evidence from Australian Eucalyptus forests suggests that mitigation of risk using prescribed burning as a fuel treatment is partial because weather and fuel dynamics are conducive to regular high intensity fires. We further examine the response of risk to treatment in eucalypt forests using landscape simulation modelling. We model how five key measures of wildfire activity that govern risk to people and property may respond to variations in rate and spatial pattern of prescribed fire. We then model effects of predicted climate change (2050 scenarios) to determine how the response of risk to treatment is likely to be altered in the future. The results indicate that a halving of risk to people and property in these forests is likely to require treatment rates of 7-10% of the area of the landscape per annum. Projections of 2050 weather conditions under climate change further substantially diminished the effect of rate of treatment. A large increase in rates of treatment (i.e. circa. 50% over current levels) would be required to counteract these effects of climate change. Such levels of prescribed burning are unlikely to be financially feasible across eucalypt dominated vegetation in south eastern Australia. Despite policy imperatives to expand fuel treatment, a reduction rather than an elimination of risk will result. Multi-faceted strategies will therefore be required for the management of risk.

A British Society of Paediatric Gastroenterology, Hepatology and Nutrition survey of the effectiveness and safety of adalimumab in children with inflammatory bowel disease

BACKGROUND

Adalimumab is efficacious therapy for adults with Crohn's disease (CD).

AIM

To summarise the United Kingdom and Republic of Ireland paediatric adalimumab experience.

METHODS

British Society of Paediatric Gastroenterology, Hepatology and Nutrition (BSPGHAN) members with Inflammatory Bowel Disease (IBD) patients <18 years old commencing adalimumab with at least 4 weeks follow-up. Patient demographics and details of treatment were then collected. Response and remission was assessed using the Paediatric Crohn's Disease Activity Index (PCDAI)/Physicians Global Assessment (PGA).

RESULTS

Seventy-two patients [70 CD, 1 ulcerative colitis (UC), 1 IBD unclassified (IBDU)] from 19 paediatric-centres received adalimumab at a median age of 14.8 (IQR 3.1, range 6.1-17.8) years; 66/70 CD (94%) had previously received infliximab. A dose of 80 mg then 40 mg was used for induction in 41(59%) and 40 mg fortnightly for maintenance in 61 (90%). Remission rates were 24%, 58% and 41% at 1, 6 and 12 months, respectively. Overall 43 (61%) went into remission at some point, with 24 (35%) requiring escalation of therapy. Remission rates were higher in those on concomitant immunosuppression cf. those not on immunosuppression [34/46 (74%) vs. 9/24 (37%), respectively, (χ(2) 8.8, P=0.003)]. There were 15 adverse events (21%) including four (6%) serious adverse events with two sepsis related deaths in patients who were also on immunosuppression and home parenteral nutrition (3% mortality rate).

CONCLUSIONS

Adalimumab is useful in treatment of refractory paediatric patients with a remission rate of 61%. This treatment benefit should be balanced against side effects, including in this study a 3% mortality rate.

Circulating ghrelin exists in both lipoprotein bound and free forms

Introduction

Ghrelin is a gastric peptide that has been implicated in the development of obesity and cardiovascular disease. It has been reported that ghrelin binds to lipoproteins, although the different binding patterns of acylated ghrelin (AG) and unacylated ghrelin (UAG) are still to be determined.

Methods

Lipoprotein fractions were generated using a self-generating iodixanol gradient. AG and UAG were measured using specific enzyme immunoassays.

Results

AG bound to all lipoproteins in approximately equal concentrations (VLDL 26%, LDL 22%, HDL 23%) and was present as a plasma protein (27%). UAG bound more specifically to HDL (49%) and was present as a plasma protein (48%).

Conclusions

The different binding patterns of AG and UAG may have significant implications for their biological effects, including roles in energy metabolism, the development of obesity and potentially in the modulation of cardiovascular disease.

The glial cell response to a viral vector in the aged brain

The normal aged brain undergoes pro-inflammatory changes. We investigated the effect of injecting a potential inflammatory stimulus, an adenoviral vector, on the response of microglia and astroglia in the aged brain. Groups of young (4 months) and old (31 months) male C57BL/Icrfat mice received a unilateral injection into the striatum of adenoviral vector encoding the LacZ gene. After 48 h, the mice were killed and the brains analysed for numbers of activated microglia and macrophages using the biotinylated lectin Griffonia simplicifolia as a marker; astroglia were identified by immunohistochemistry for glial fibrillary acidic protein (GFAP). The cell counts were analysed using two-way analysis of variance (anova). Transgene expression was assessed by beta-galactosidase histochemistry. The numbers of activated microglia in the striatum increased in response to the adenovirus in both young [contralateral 19.5 (3.7), ipsilateral 36 (3.0)] and old [contralateral 23.1 (9.6), ipsilateral 40.8 (6.9)] mice (two-way anova; P < 0.0001), but there was no significant difference between the two age groups. There was a significant age-related increase in the number of GFAP-positive astroglia in the uninjected, contralateral striatum [4 months, 2.5 (1.4); 31 months, 29.7 (9.3)] (two-way anova; P < 0.0001). However, there was no difference in response to the adenovirus in both young [contralateral 2.5 (1.4), ipsilateral 3.2 (1.2)] and old [contralateral 29.7 (9.3), ipsilateral 28.9 (8.2)] mice. We conclude that even though it has been argued that the aged brain is in a pro-inflammatory state, under the experimental conditions used in this study, there was no difference in the nature of the immune response between young and old mice of this strain to an adenoviral load.

Cardiovascular response to graded lower body negative pressure in young and elderly man

Lower body negative pressure (LBNP) reduces central venous pressure (CVP) and cardiac output. The elderly are reported to have a limited capacity to increase cardiac output by increasing heart rate (HR), are especially dependent on end diastolic volume to maintain stroke volume and therefore should be especially vulnerable to LBNP. The present study compared the effects of LBNP in the young and old. Stroke volume was assessed non-invasively as stroke distance (SD) by aortovelography. Two groups of healthy male volunteers were studied: eight young (29.7 +/- 2.0 years, mean +/- S.E.M.) and nine old (70.1 +/- 0.9 years). LBNP was applied progressively at 17.5, 35 and 50 mmHg in 20 min steps, with measurements taken during each steady state. There were similar, significant, falls in CVP in both groups. SD fell significantly in both groups from respective control values of 24.8 +/- 1.6 and 16.6 +/- 0.9 cm to 12.5 +/- 1.3 and 8.9 +/- 0.4 cm at a LBNP of 50 mmHg. Although SD in the elderly was significantly lower than in the young, the LBNP-induced changes were not different between groups. Both groups produced similar significant increases in vascular resistance, HR, plasma vasopressin (AVP) and noradrenaline. Mean arterial blood pressure (MBP) and plasma adrenaline did not change significantly. Therefore healthy old men respond to LBNP in a similar manner to the young, although MBP and SD are regulated around different baselines in the two groups.

Color categories are not universal: replications and new evidence from a stone-age culture

The authors sought to replicate and extend the work of E. Rosch Heider (1972) on the Dani with a comparable group from Papua, New Guinea, who speak Berinmo, which has 5 basic color terms. Naming and memory for highly saturated focal, non-focal, and low-saturation stimuli from around the color space were investigated. Recognition of desaturated colors was affected by color vocabulary. When response bias was controlled, there was no recognition advantage for focal stimuli. Paired-associate learning also failed to show an advantage for focal stimuli. Categorical Perception effects for both English and Berinmo were found, but only at the boundaries of existing linguistic categories. It is concluded that possession of linguistic categories facilitates recognition and influences perceptual judgments.

Development of an automated method for determining oil in water by direct aqueous supercritical fluid extraction coupled on-line with infrared spectroscopy

A direct aqueous supercritical fluid extraction (SFE) system was developed which can be directly interfaced to an infrared spectrometer for the determination of oil in water. The technique is designed to provide an environmentally clean, automated alternative to established IR methods for oil in water analysis which require the use of restricted organic solvents. The SFE-FTIR method involves minimum sample handling stages, with on-line analysis of a 500 ml water sample being complete within 15 min. Method accuracy for determining water samples spiked with gasoline, white spirit, kerosene, diesel or engine oil was 81-100% with precision (RSD) ranging from 3 to 17%. An independent evaluation determined a 2 ppm limit of quantification for diesel in industrial effluents. The results of a comparative study involving an established IR method and the SFE-FTIR method indicate that oil levels calculated using an accepted equation which includes coefficients derived from reference hydrocarbon standards may result in significant errors. A new approach permitted the derivation of quantification coefficients for the SFE-FTIR analyses which provided improved results. In situations where the identity of the oil to be analysed is known, a rapid off-line SFE-FTIR system calibration procedure was developed and successfully applied to various oils. An optional in-line silica gel clean-up procedure incorporated within the SFE-FTIR system enables the same water sample to be analysed for total oil content including vegetable oils and selectively for petroleum oil content within a total of 20 min. At the end of an analysis the SFE system is cleaned using an in situ 3 min clean cycle.

A multi-modality assay platform for ultra-high throughput screening

The demand for increased throughput during primary screening using less reagents is changing the way of drug discovery. Searching for hits using high throughput screening in 96-well format plates is being replaced by the use of higher density plates, such as 384 and 1536-well formats. The analysis of radiometric assays by scintillation counters is becoming limiting since only 12 wells can be counted at a time. Charged coupled device (CCD) camera based instruments, that image the whole plate in one exposure, speed up detection and are compatible with any microplate footprint. Researchers are also demanding a choice of detection methods, including fluorescence, luminescence and radioactivity, and require imagers suitable for all applications. LEADseeker Homogenous Imaging System is a multi-modality platform offering imaging technology and assay toolboxes for radiometric, fluorescent and luminescent based assays. LEADseeker allows the very rapid analysis of high density formats enabling ultra-high throughput screening of a range of biological assays. Research areas that can be studied using this system include enzyme assays, receptor binding and molecular interactions.

Oedema and glial cell involvement in the aged mouse brain after permanent focal ischaemia

This study examines the effect of age on oedema and brain swelling, and associated glial cell involvement on the size of the lesion in two models of permanent, focal cerebral ischaemia. Ischaemia was induced in male C57BL/Icrfat mice (4-6 and 26-31-month-old) by middle cerebral artery (MCA) occlusion using either electrocoagulation after craniotomy (MCA/craniotomy), or by an intraluminal filament through the carotid artery (MCA/icf). Twenty-four hours after inducing ischaemia, brain swelling and lesion size were measured in young and aged mice, and cerebral oedema by wet/dry brain weights. Histopathology and immunocytochemistry were performed on a separate set of perfusion fixed brains. The MCA/icf technique produced a significantly larger lesion than MCA/craniotomy in both age groups. The percentage of water taken into the brain was significantly greater after MCA/icf, with aged mice showing the greatest increase. When lesion size was corrected for brain swelling there was no age-related increase in the size of the lesion. The numbers of microglia and astroglia increased significantly in the parietal cortex of aged control animals, and there were qualitative differences in the glial response between the two stroke models. This study emphasizes the importance of age in models of permanent focal ischaemia, with oedema clearly being a significant factor. Differ-ences in the responsiveness of the glial cell population with age may be of fundamental importance in the progress of ischaemic brain damage.

Color categories are not universal: replications and new evidence from a stone-age culture

The authors sought to replicate and extend the work of E. Rosch Heider (1972) on the Dani with a comparable group from Papua, New Guinea, who speak Berinmo, which has 5 basic color terms. Naming and memory for highly saturated focal, non-focal, and low-saturation stimuli from around the color space were investigated. Recognition of desaturated colors was affected by color vocabulary. When response bias was controlled, there was no recognition advantage for focal stimuli. Paired-associate learning also failed to show an advantage for focal stimuli. Categorical Perception effects for both English and Berinmo were found, but only at the boundaries of existing linguistic categories. It is concluded that possession of linguistic categories facilitates recognition and influences perceptual judgments.

Response to dehydration in elderly patients in long-term care

Elderly patients in long-term care have a high plasma osmolality (pOSM) and associated increased mortality. In these patients, we examined pOSM, thirst (visual analogue scale, VAS) and arginine vasopressin (AVP) response to 16-hour dehydration and 2-hour rehydration. Twelve patients were randomly divided into two groups (A & B). Group A had their fluid balance monitored for two weeks, group B did not. Single measurements of VAS, pOSM and AVP were conducted on days 0, 7 and 13. Dehydration tests were conducted in both groups at the start of the study (DAY 1), and at the end of the two-week period (DAY 14). There were no significant differences between group A and B, so the results are presented for the two groups combined. There was a significant increase in both pOSM and VAS during dehydration, and a significant fall in both variables during rehydration [F (9,99) = 18.69, p < 0.001, and F(9,99) = 11.25, p < 0.001, respectively]. Plasma AVP did not change significantly during either dehydration or rehydration [F (9,99) = 0.59, p = 0.8]. There were no significant differences in response for any of the three variables between DAY 1 and DAY 14. We conclude that elderly patients in long-term care exhibit changes in thirst and osmolality during dehydration and rehydration, and that these responses are reproducible. The lack of a significant AVP response requires further investigation.

Production of consistent crush lesions of murine skeletal muscle in vivo using an electromechanical device

The crush model of injury in skeletal muscle is widely used in the investigation of tissue degeneration and regeneration. Previously, such trauma has been induced by using forceps to crush the muscle, commonly applying sufficient pressure to bring the mid-arms of the forceps together. This report introduces a reliable electromechanical device designed to generate reproducible focal lesions in skeletal muscle of mice. The tibialis anterior was crushed in 17 young adult mice. Two days after injury, the muscles were examined microscopically. By morphometric analysis, it was determined that the volumes of the lesions produced were similar (mean 0.499 mm3 +/- 0.098, range 0.278 - 0.601 mm3), and that the full extent of the damaged muscle was easily distinguished and readily quantifiable. This will allow a more precise comparison in future investigations into regenerative differences between age groups, satellite cell activation and the inflammatory response.

A randomised controlled trial and cost analysis of problem-solving treatment for emotional disorders given by community nurses in primary care

BACKGROUND

We set out to investigate whether community nurses could be trained in problem-solving therapy and, once trained, how effective they would be in treating emotional disorders in primary care.

METHOD

Seventy patients with an emotional disorder in primary care were randomly allocated to receive either problem-solving therapy from a trained community nurse or treatment as usual from their general practitioner. Interview and self-rated assessments of clinical and economic outcome were made pretreatment, at eight weeks and at 26 weeks after treatment.

RESULTS

There was no difference in clinical outcome between patients who received problem-solving treatment and patients who received the general practitioner's usual treatment. However, patients who received problem-solving treatment had fewer disability days and fewer days off work. The health care cost of problem-solving was greater than that of the general practitioner's usual treatment but this was more than offset by savings in the cost of days off work.

CONCLUSIONS

Problem-solving treatment can be given by trained community nurses. The clinical effectiveness and cost-benefit of the treatment will depend on the selection of appropriate patients.

Perceptual learning of stereoacuity

It has often been noted that with repeated exposure to random-dot stereograms the time required to perceived depth decreases. Further, with extensive practice, stereoacuity thresholds have been shown to decrease. For both types of learning some researchers have reported specificity of the improvements to retinal location, and have thus suggested that the learning may be localised at early levels of visual processing, such as in primary visual cortex. However, these studies have not adequately ruled out the possibility that the specificity shown may be due to the operation of selective-spatial-attention mechanisms. In the present study this possibility was examined by training observers to judge the relative depth of a pair of stereograms presented equally often in two spatial locations, but stimuli were only presented with one direction of disparity (ie crossed or uncrossed) in any one location. Results indicated that, as expected, observers' judgements improved with practice. However, this improvement transferred completely to stimuli presented with the other direction of disparity in each location. Thus, it is argued that previous findings of retinal-location-specific improvements in stereoacuity may well be due to selective-spatial-attention mechanisms, rather than to learning localised at an early level of visual processing.

Age-related postreceptor mechanisms: changes in adenylate cyclase but not phosphodiesterase in isolated mouse renal medullary collecting ducts

Urine concentrating ability declines with increasing age, partly due to an impaired response of kidney medullary collecting ducts to the antidiuretic hormone, vasopressin. We investigated this change in isolated mouse medullary collecting ducts by measuring the activity of adenylate cyclase and phosphodiesterase, which catalyse the formation and hydrolysis of cAMP, respectively. Adenylate cyclase activity was measured in the presence of vasopressin (which stimulates adenylate cyclase via the receptor) or forskolin (which directly stimulates the catalytic subunit). We showed an age-related decrease in the catalytic subunit of adenylate cyclase, and no difference in the activity of phosphodiesterase, indicating that a reduction in the catalytic subunit of adenylate cyclase contributes towards the age-related decrease in cyclic AMP response of kidney to vasopressin.

Age-associated alterations in thirst and arginine vasopressin in response to a water or sodium load

We have examined simultaneous changes in thirst, plasma osmolality and arginine vasopressin, after oral water loading or hypertonic saline infusion. The studies were carried out in the same subjects, comprising young controls aged 26.8 years (SD 4.8, n = 10) and health status-defined elderly people aged 72.1 years (SD 3.1, n = 10). Water loading caused significant falls in plasma osmolality (p < 0.001) and thirst (p < 0.001), but there was no variation with age. Infusion with 462 mmol/l of sodium chloride increased plasma osmolality significantly (p < 0.001), but there was no variation with age (p = 0.12). The perception of thirst during the osmotic loading experiment was recorded differently by the two age groups (p < 0.0001). However, linear regression analysis showed no age difference in the relationship between thirst and plasma osmolality during osmotic loading. During osmotic loading the relationship between the plasma concentration of arginine vasopressin in response to increasing plasma osmolality varied significantly (slope: p = 0.02; intercept: p = 0.02). Plasma arginine vasopressin rose more rapidly with increasing plasma osmolality in old subjects.

Dual-channel laser scanning microscopy for the identification and quantification of proliferating skeletal muscle satellite cells following synergist ablation

Proliferating skeletal muscle satellite cells are the source of additional myonuclei which allow skeletal muscle to grow and regenerate. Previously, proliferating satellite cells were identified in situ by techniques which were limited either by tissue processing time or inability to observe complete muscle sections, or by errors made in separating these cells from proliferating nonmyogenic cells. To overcome these problems a new method has been devised for the identification and quantification of proliferating satellite cells in situ by light microscopy. The technique involves dual-channel laser scanning imaging of whole muscle sections for the localisation of both the muscle fibre basal lamina and the cell division marker bromodeoxyuridine. Using this technique satellite cell proliferation was quantified in mouse limb muscle following synergist ablation. Dual-channel laser scanning microscopy allowed precise localisation of proliferating satellite cells in the experimental model and, after 4 d, synergist ablation was shown to have produced significant satellite cell proliferation when compared with contralateral and sham-operated controls.

A developmental study of the acquisition of colour terms in Setswana

We report a study of the acquisition of colour terms by speakers of Setswana, the language of Botswana in Southern Africa. This was carried out as a test of Berlin & Kay's theory of colour term universals, on a language with less than the maximum complement of eleven basic colour terms, and in order to document changes in Setswana under the impact of economic development. Seventy-seven five- to nine-year-olds were studied on two colour tasks: elicited lists and colour naming. In general the data were consistent with Berlin & Kay's theory: the rank order of frequency of correct use of colour terms was similar to the order of the Berlin & Kay hierarchy; and primary colour terms were offered more frequently and were more likely to be used correctly than secondary colour terms. The use of English colour terms was prevalent, especially amongst the younger groups, but they functioned as substitutes for Setswana terms, rather than as a means to fill the vacant basic colour term slots.

Fluid balance in elderly patients following acute stroke

We studied the relationship between plasma osmolality, arginine vasopressin (AVP), and fluid input in patients during the acute phase of a first stroke. Fifteen consecutive patients were studied (median age 79) and their blood sampled on days 0, 1, 2, 3, 7 and 14. Plasma osmolality was related to fluid input over days 0-3 (p = 0.0013) and AVP over 14 days (p less than 0.001). Patients with a poor outcome had higher AVP concentrations (p = 0.02). Those on intravenous fluids received a higher volume (p less than 0.01) and had a lower plasma osmolality (p = 0.04). The results of this preliminary study indicate that a standard regime for fluid input is inappropriate.

Influence of age on plasma osmolality: a community study

We have shown an age-associated increase in plasma osmolality (p less than 0.001) in 152 randomly selected subjects, living in the community. In the old [mean age 78.0 (7.5) years] the plasma osmolality was 302.2 (300.6-303.8) mOsmol/kg compared with 291.2 (290.0-292.3) mOsmol/kg in the young [39.2 (11.2) years] (p less than 0.0001). In a further group of 20 screened, health status defined, elderly subjects the plasma osmolality was 298.1 (295.9-300.3) mOsmol/kg, which was significantly higher than the young group (p less than 0.0001) but lower than the unscreened old subjects (p = 0.005). The variance was also significantly lower (p = 0.03). The results may reflect a loosening of homoeostatic control and highlight the need for care in subject selection in studies of ageing.