A comparison of visual hallucinations across disorders

Research into hallucinations typically regards them as single sensory or unimodal experiences leading to a comparative neglect of co-occurring multi-sensory hallucinations (MSH). People with psychosis who have visual hallucinations (VH) report high rates of hallucinations in other senses (auditory, olfactory, tactile). However, it is not known if this is similar to other groups who report VH. Consequently, this study explored MSH in four different patient groups who all had current VH. Archival data from standardised assessments of visual hallucinations in people with psychosis (n = 22), eye disease (ED) (n = 82), Lewy body Dementia (LBD) (n = 41), and Parkinson's disease (PD) (n = 41) determined the presence of MSH. People with psychosis and visual hallucinations reported significantly higher rates of MSH (auditory, 73%; tactile, 82%; olfactory/gustatory hallucinations, 27%) than the LBD group (auditory, 21%; tactile, 28%; olfactory/gustatory, 6%), ED (auditory, 1%; tactile, 11%; olfactory/gustatory, 0%) and PD patients (auditory, 3%; tactile, 8%; olfactory/gustatory, 3%). Regardless of diagnostic grouping, participants with MSH reported greater conviction that the VH were real, and reported greater distress. People with psychosis with VH report high rates of MSH unlike groups of older adults with VH. These between group differences in MSH prevalence have implications for clinical practice and theory.

Shifting Paradigms in the Mechanics of Nectar Extraction and Hummingbird Bill Morphology

As functional morphologists, we aim to connect structures, mechanisms, and emergent higher-scale phenomena (e.g., behavior), with the ulterior motive of addressing evolutionary patterns. The fit between flowers and hummingbird bills has long been used as an example of impressive co-evolution, and hence hummingbirds' foraging behavior and ecological associations have been the subject of intense study. To date, models of hummingbird foraging have been based on the almost two-centuries-old assumption that capillary rise loads nectar into hummingbird tongue grooves. Furthermore, the role of the bill in the drinking process has been overlooked, instead considering it as the mere vehicle with which to traverse the corolla and access the nectar chamber. As a scientific community, we have been making incorrect assumptions about the basic aspects of how hummingbirds extract nectar from flowers. In this article, we summarize recent advances on drinking biomechanics, morphological and ecological patterns, and selective forces involved in the shaping of the hummingbird feeding apparatus, and also address its modifications in a previously unexpected context, namely conspecific and heterospecific fighting. We explore questions such as: how do the mechanics of feeding define the limits and adaptive consequences of foraging behaviors? Which are the selective forces that drive bill and tongue shape, and associated sexually dimorphic traits? And finally, what are the proximate and ultimate causes of their foraging strategies, including exploitative and interference competition? Increasing our knowledge of morphology, mechanics, and diversity of hummingbird feeding structures will have implications for understanding the ecology and evolution of these remarkable animals.

Accurate measurement of androgen after androgen esters: problems created by ex vivo esterase effects and LC-MS/MS interference

Background

Ex vivo androgen prodrug conversion by blood esterases after oral androgen ester administration may result in an overestimation of the measured blood androgens.

Objective

We investigated whether blood collection tubes with esterase inhibitors decreased the conversion of testosterone undecanoate (TU) and dimethandrolone undecanoate (DMAU) to their active metabolites, testosterone (T), and dimethandrolone (DMA), providing a more accurate assessment of circulating T/DMA levels.

Methods

Blood was collected in tubes with/without esterase inhibitors from: (i) four healthy and four hypogonadal men receiving no androgens and spiked ex vivo with TU/DMAU; (ii) four men taking oral TU (Andriol^®); and (iii) eight hypogonadal men dosed with oral 316 mg TU and 15 healthy men with 200 mg DMAU. T/DMA levels were measured by LC‐MS/MS.

Results

Sodium fluoride (NaF, an esterase inhibitor) decreased measured T levels by 14.2% in men not receiving TU. Increasing amounts of TU/DMAU added to blood collected into plain tubes resulted in a concentration‐dependent overestimation of T/DMA that was reduced by collecting blood into NaF tubes (by 30–85%), and keeping samples at 4 °C and minimizing time prior to centrifugation. After oral TU/DMAU administration to men, when TU/DMAU levels were >15/10 ng/mL, respectively, blood collected in NaF tubes yielded lower measured T concentrations by 15–30% and DMA by 22% due to an additional inhibitory effect of NaF on blood esterases.

Conclusion

NaF directly lowers plasma T/DMA levels measured by LC‐MS/MS and also inhibits blood esterase activity. Overestimation of T/DMA in blood collected in tubes without NaF after oral TU/DMAU administration is important for pharmacokinetics studies in drug development clinical trials but may have limited impact in clinical practice/utilization because the differences between measured and true androgen values are modest and the wide therapeutic androgen efficacy ranges obviate the need for highly accurate androgen measurements during therapy.

Escaping blood-fed malaria mosquitoes minimize tactile detection without compromising on take-off speed

To escape after taking a blood meal, a mosquito must exert forces sufficiently high to take off when carrying a load roughly equal to its body weight, while simultaneously avoiding detection by minimizing tactile signals exerted on the host's skin. We studied this trade-off between escape speed and stealth in the malaria mosquito Anopheles coluzzii using 3D motion analysis of high-speed stereoscopic videos of mosquito take-offs and aerodynamic modeling. We found that during the push-off phase, mosquitoes enhanced take-off speed using aerodynamic forces generated by the beating wings in addition to leg-based push-off forces, whereby wing forces contributed 61% of the total push-off force. Exchanging leg-derived push-off forces for wing-derived aerodynamic forces allows the animal to reduce peak force production on the host's skin. By slowly extending their long legs throughout the push-off, mosquitoes spread push-off forces over a longer time window than insects with short legs, thereby further reducing peak leg forces. Using this specialized take-off behavior, mosquitoes are capable of reaching take-off speeds comparable to those of similarly sized fruit flies, but with weight-normalized peak leg forces that were only 27% of those of the fruit flies. By limiting peak leg forces, mosquitoes possibly reduce the chance of being detected by the host. The resulting combination of high take-off speed and low tactile signals on the host might help increase the mosquito's success in escaping from blood-hosts, which consequently also increases the chance of transmitting vector-borne diseases, such as malaria, to future hosts.

Into rude air: hummingbird flight performance in variable aerial environments

Hummingbirds are well known for their ability to sustain hovering flight, but many other remarkable features of manoeuvrability characterize the more than 330 species of trochilid. Most research on hummingbird flight has been focused on either forward flight or hovering in otherwise non-perturbed air. In nature, however, hummingbirds fly through and must compensate for substantial environmental perturbation, including heavy rain, unpredictable updraughts and turbulent eddies. Here, we review recent studies on hummingbirds flying within challenging aerial environments, and discuss both the direct and indirect effects of unsteady environmental flows such as rain and von Kármán vortex streets. Both perturbation intensity and the spatio-temporal scale of disturbance (expressed with respect to characteristic body size) will influence mechanical responses of volant taxa. Most features of hummingbird manoeuvrability remain undescribed, as do evolutionary patterns of flight-related adaptation within the lineage. Trochilid flight performance under natural conditions far exceeds that of microair vehicles at similar scales, and the group as a whole presents many research opportunities for understanding aerial manoeuvrability.This article is part of the themed issue 'Moving in a moving medium: new perspectives on flight'.

Recall of threat material is modulated by self or other referencing in people with high or low levels of non-clinical paranoia

BACKGROUND AND OBJECTIVES

Biased processing of negatively valenced, and particularly threat-related material plays an important role in the development of paranoid thinking. This has been demonstrated by superior memory for threat-related information in patients with persecutory delusions and in non-clinical paranoia-prone participants. This study examined how emotional material was recalled having been encoded in relation to one self or to another person, in people high or low in paranoid ideation. It was predicted that people high in paranoia would recall more threat related material about others than people low in paranoia owing to being particularly alert to threats from other people.

METHODS

Participants who reported high (N = 30) or low (N = 30) levels of sub-clinical paranoid thinking were presented with a series of threat-related and positive words and were asked to process them in terms of the self, or in terms of a fictional character.

RESULTS

As predicted, when words were processed in terms of another person, the high paranoia group recalled more threat-related words than positive words, but when words had been processed in terms of the self, recall of threat-related and positive words did not differ. In contrast, there was no interaction between word-valence and referent in the low paranoia group.

LIMITATIONS

These findings are drawn from an analogue sample. Replication in a sample of clinical participants who report persecutory delusions is required.

CONCLUSIONS

People high in sub-clinical paranoid ideation recalled threat preferentially in relation to other people. Such information processing biases may help understand the development and maintenance of persecutory beliefs.

Complex visual hallucinations and attentional performance in eye disease and dementia: a test of the Perception and Attention Deficit model

OBJECTIVE

This study aimed to test the prediction from the Perception and Attention Deficit model of complex visual hallucinations (CVH) that impairments in visual attention and perception are key risk factors for complex hallucinations in eye disease and dementia.

METHODS

Two studies ran concurrently to investigate the relationship between CVH and impairments in perception (picture naming using the Graded Naming Test) and attention (Stroop task plus a novel Imagery task). The studies were in two populations-older patients with dementia (n = 28) and older people with eye disease (n = 50) with a shared control group (n = 37). The same methodology was used in both studies, and the North East Visual Hallucinations Inventory was used to identify CVH.

RESULTS

A reliable relationship was found for older patients with dementia between impaired perceptual and attentional performance and CVH. A reliable relationship was not found in the population of people with eye disease.

CONCLUSIONS

The results add to previous research that object perception and attentional deficits are associated with CVH in dementia, but that risk factors for CVH in eye disease are inconsistent, suggesting that dynamic rather than static impairments in attentional processes may be key in this population.

Determination of renewable energy yield from mixed waste material from the use of novel image analysis methods

Two novel techniques are presented in this study which together aim to provide a system able to determine the renewable energy potential of mixed waste materials. An image analysis tool was applied to two waste samples prepared using known quantities of source-segregated recyclable materials. The technique was used to determine the composition of the wastes, where through the use of waste component properties the biogenic content of the samples was calculated. The percentage renewable energy determined by image analysis for each sample was accurate to within 5% of the actual values calculated. Microwave-based multiple-point imaging (AutoHarvest) was used to demonstrate the ability of such a technique to determine the moisture content of mixed samples. This proof-of-concept experiment was shown to produce moisture measurement accurate to within 10%. Overall, the image analysis tool was able to determine the renewable energy potential of the mixed samples, and the AutoHarvest should enable the net calorific value calculations through the provision of moisture content measurements. The proposed system is suitable for combustion facilities, and enables the operator to understand the renewable energy potential of the waste prior to combustion.

Structure of the vortex wake in hovering Anna's hummingbirds (Calypte anna)

Hummingbirds are specialized hoverers for which the vortex wake has been described as a series of single vortex rings shed primarily during the downstroke. Recent findings in bats and birds, as well as in a recent study on Anna's hummingbirds, suggest that each wing may shed a discrete vortex ring, yielding a bilaterally paired wake. Here, we describe the presence of two discrete rings in the wake of hovering Anna's hummingbirds, and also infer force production through a wingbeat with contributions to weight support. Using flow visualization, we found separate vortices at the tip and root of each wing, with 15% stronger circulation at the wingtip than at the root during the downstroke. The upstroke wake is more complex, with near-continuous shedding of vorticity, and circulation of approximately equal magnitude at tip and root. Force estimates suggest that the downstroke contributes 66% of required weight support, whereas the upstroke generates 35%. We also identified a secondary vortex structure yielding 8-26% of weight support. Lift production in Anna's hummingbirds is more evenly distributed between the stroke phases than previously estimated for Rufous hummingbirds, in accordance with the generally symmetric down- and upstrokes that characterize hovering in these birds.

Cognitive therapy for people with a schizophrenia spectrum diagnosis not taking antipsychotic medication: an exploratory trial

BACKGROUND

Although antipsychotic medication is the first line of treatment for schizophrenia, many service users choose to refuse or discontinue their pharmacological treatment. Cognitive therapy (CT) has been shown to be effective when delivered in combination with antipsychotic medication, but has yet to be formally evaluated in its absence. This study evaluates CT for people with psychotic disorders who have not been taking antipsychotic medication for at least 6 months.

METHOD

Twenty participants with schizophrenia spectrum disorders received CT in an open trial. Our primary outcome was psychiatric symptoms measured using the Positive and Negative Syndromes Scale (PANSS), which was administered at baseline, 9 months (end of treatment) and 15 months (follow-up). Secondary outcomes were dimensions of hallucinations and delusions, self-rated recovery and social functioning.

RESULTS

T tests and Wilcoxon's signed ranks tests revealed significant beneficial effects on all primary and secondary outcomes at end of treatment and follow-up, with the exception of self-rated recovery at end of treatment. Cohen's d effect sizes were moderate to large [for PANSS total, d=0.85, 95% confidence interval (CI) 0.32-1.35 at end of treatment; d=1.26, 95% CI 0.66-1.84 at follow-up]. A response rate analysis found that 35% and 50% of participants achieved at least a 50% reduction in PANSS total scores by end of therapy and follow-up respectively. No patients deteriorated significantly.

CONCLUSIONS

This study provides preliminary evidence that CT is an acceptable and effective treatment for people with psychosis who choose not to take antipsychotic medication. An adequately powered randomized controlled trial is warranted.

A wing-assisted running robot and implications for avian flight evolution

DASH+Wings is a small hexapedal winged robot that uses flapping wings to increase its locomotion capabilities. To examine the effects of flapping wings, multiple experimental controls for the same locomotor platform are provided by wing removal, by the use of inertially similar lateral spars, and by passive rather than actively flapping wings. We used accelerometers and high-speed cameras to measure the performance of this hybrid robot in both horizontal running and while ascending inclines. To examine consequences of wing flapping for aerial performance, we measured lift and drag forces on the robot at constant airspeeds and body orientations in a wind tunnel; we also determined equilibrium glide performance in free flight. The addition of flapping wings increased the maximum horizontal running speed from 0.68 to 1.29 m s⁻¹, and also increased the maximum incline angle of ascent from 5.6° to 16.9°. Free flight measurements show a decrease of 10.3° in equilibrium glide slope between the flapping and gliding robot. In air, flapping improved the mean lift:drag ratio of the robot compared to gliding at all measured body orientations and airspeeds. Low-amplitude wing flapping thus provides advantages in both cursorial and aerial locomotion. We note that current support for the diverse theories of avian flight origins derive from limited fossil evidence, the adult behavior of extant flying birds, and developmental stages of already volant taxa. By contrast, addition of wings to a cursorial robot allows direct evaluation of the consequences of wing flapping for locomotor performance in both running and flying.

Specific attentional impairments and complex visual hallucinations in eye disease

OBJECTIVE

To test the prediction by the Perception and Attention Deficit (PAD) model of complex visual hallucinations that cognitive impairment, specifically in visual attention, is a key risk factor for complex hallucinations in eye disease.

METHODS

Two studies of elderly patients with acquired eye disease investigated the relationship between complex visual hallucinations (CVH) and impairments in general cognition and verbal attention (Study 1) and between CVH, selective visual attention and visual object perception (Study 2). The North East Visual Hallucinations Inventory was used to classify CVH.

RESULTS

In Study 1, there was no relationship between CVH (n=10/39) and performance on cognitive screening or verbal attention tasks. In Study 2, participants with CVH (n=11/31) showed poorer performance on a modified Stroop task (p<0.05), a novel imagery-based attentional task (p<0.05) and picture (p<0.05) but not silhouette naming (p=0.13) tasks. Performance on these tasks correctly classified 83% of the participants as hallucinators or non-hallucinators.

CONCLUSIONS

The results suggest that, consistent with the PAD model, complex visual hallucinations in people with acquired eye disease are associated with visual attention impairment.

Parasite-induced fruit mimicry in a tropical canopy ant

Some parasites modify characteristics of intermediate hosts to facilitate their consumption by subsequent hosts, but examples of parasite-mediated mimicry are rare. Here we report dramatic changes in the appearance and behavior of nematode-parasitized ants such that they resemble ripe fruits in the tropical rain forest canopy. Unlike healthy ants, which are completely black, infected ants have bright red, berry-like gasters full of parasite eggs. The infected gasters are held in a conspicuous elevated position as the ants are walking, and they are easily detached from living ants, which also exhibit reduced defensive responses. This combination of changes presumably makes the infected ants attractive to frugivorous birds, which ingest the red gasters and pass the parasite eggs in their feces. The feces are collected by ants and fed to the developing brood, thus completing the cycle. This is the first documentation of parasites causing apparent fruit mimicry in an animal host to complete their life cycle.

Allometry of hummingbird lifting performance

Vertical lifting performance in 67 hummingbird species was studied across a 4000 m elevational gradient. We used the technique of asymptotic load-lifting to elicit maximum sustained muscle power output during loaded hovering flight. Our analysis incorporated direct measurements of maximum sustained load and simultaneous wingbeat kinematics, together with aerodynamic estimates of mass-specific mechanical power output, all within a robust phylogenetic framework for the Trochilidae. We evaluated key statistical factors relevant to estimating slopes for allometric relationships by performing analyses with and without phylogenetic information, and incorporating species-specific measurement error. We further examined allometric relationships at different elevations because this gradient represents a natural experiment for studying physical challenges to animal flight mechanics. Maximum lifting capacity (i.e. vertical force production) declined with elevation, but was either isometric or negatively allometric with respect to both body and muscle mass, depending on elevational occurrence of the corresponding taxa. Maximum relative muscle power output exhibited a negative allometry with respect to muscle mass, supporting theoretical predictions from muscle mechanics.

Limits to vertical force and power production in bumblebees (Hymenoptera: Bombus impatiens)

Maximum vertical forces produced by flying animals can be difficult to identify unequivocally, but potentially indicate general limits to aerodynamic force and muscle power output. We used two methods (i.e. incremental addition of supplemental mass and asymptotic load lifting) to determine both the intraspecific allometry of and methodological differences in estimates of maximum flight performance for the bumblebee Bombus impatiens. We found that incremental mass addition underestimated maximum lifting capacity by approximately 18% relative to values obtained by asymptotically increasing the applied load during a lifting bout. In asymptotic loading, bumblebees lifted on average 53% of their body weight, and demonstrated a significantly negative allometry of maximum aerodynamic force production relative to thoracic muscle mass. Estimates of maximum body mass-specific mechanical power output increased intraspecifically with body mass to the 0.38–0.50 power, depending on values assumed for the profile drag coefficient. We also found a significant reduction in vertical force production when both hindwings were removed. Limits to load-lifting capacity ultimately co-occur with an upper bound on stroke amplitude (∼145 deg.). Although thoracic muscle mass showed positive allometry, overall load-lifting performance exhibited significant size-dependent degradation.

Cognitive behaviour therapy in patients with schizophrenia who are not prescribed antipsychotic medication: a case series

OBJECTIVES

Cognitive behaviour therapy (CBT) as an adjunct to medication has been shown to improve symptom management in patients with schizophrenia. However, little is understood about the value of CBT for people who are not prescribed antipsychotic medication.

DESIGN

A post hoc case series design was used to examine the outcome data of three participants selected from a randomized controlled trial for CBT for schizophrenia. The participants were included if they had received CBT and were not prescribed antipsychotic medication during active treatment.

RESULTS

The three patients improved on outcome measures of psychopathology, depression, or negative symptoms, some to a clinically significant degree.

CONCLUSIONS

CBT is a feasible treatment for people with schizophrenia who are not prescribed antipsychotic medication. It may be a valuable alternative to medication in treating symptoms of schizophrenia.

The role of visual cues in directed aerial descent of Cephalotes atratus workers (Hymenoptera: Formicidae)

Animals often depend on properties of reflected light (e.g. color,brightness) to locate resources. We compared reflectance properties of tree trunks with surrounding vegetation, and examined how differences in reflectance profiles of surrogate tree trunks (red, yellow, green, blue,black, gray, dark gray and white sheets) affected the directed aerial descent of worker Cephalotes atratus (L.) ants. Across the visual spectrum,tree trunk reflectance was 2–10 times higher than the surrounding foliage and differed among trees. In two separate experiments, one with colored sheets and one with black, white and gray sheets, nearly half (42% and 47%, respectively) of falling ants directed their descent to a bright white sheet when given a choice of target colors or shades of gray. When colored and gray sheets were presented individually, landing frequencies were lower than expected for all except white sheets. Glide performance was highly variable,but there was a tendency for higher glide indices to be associated with the white sheet relative to the green sheet. We conclude that visually mediated aerial behavior in falling canopy ants is strongly influenced by reflectance properties of the target object, specifically brightness, and correlates with preferred natural targets of tree trunks.

Common variable immune deficiency: respiratory manifestations, pulmonary function and high-resolution CT scan findings

BACKGROUND

Common variable immune deficiency (CVID) is prone to under-diagnosis and may not reach relevant specialists until late in life. Morbidity is most commonly due to acute-on-chronic respiratory infections leading to respiratory failure.

AIM

To investigate respiratory complications, lung function and high-resolution computerized tomography scan (HRCT) findings and mortality in 47 patients with CVID.

SETTING

A regional immunology unit (Birmingham Heartlands Hospital).

DESIGN

Retrospective observational case-note study following the introduction of shared care between immunology and respiratory medicine.

RESULTS

Age at diagnosis ranged from 5 to 72 years, with a median time from development of first symptoms to diagnosis of 4.0 years. There was delay in referral between chest physicians and immunologists, (median referral time between specialities >5 years). Forty-two patients had respiratory complications, due to bronchiectasis (n=32), asthma (n=7), recurrent chest infections (n=9) without concomitant evidence of structural lung damage, and granulomatous lung disease (n=2). Spirometry was abnormal in 10/39 patients (7 obstructive, 3 restrictive). Bronchiectasis was confirmed on chest radiograph (n=9) and HRCT (n=24). Despite the high prevalence of bronchiectasis, few patients had received instruction in physiotherapy and sputum culture results were sparse.

DISCUSSION

To reduce the morbidity associated with CVID, there needs to be greater awareness of respiratory complications, particularly amongst physicians caring for such patients. Emphasis has been placed on adequate dosage of immunoglobulin, but early involvement by a respiratory physician is essential to monitor lung function and initiate optimal therapy, to minimize the occurrence and progression of lung damage.

Development of a p53 responsive GFP reporter; identification of live cells with p53 activity

p53 is among the most intensely studied human proteins because of its vital role as the prototype tumor suppressor. As a result, there are widespread applications for p53 functional analysis in biotechnology as it relates to cancer research. p53 is a potent sequence specific transcription factor, which induces the expression of a number of genes whose products mediate cell cycle arrest and apoptosis. Because the tumor suppressor activity of p53 is dependent on its transcription regulatory function, we have undertaken to develop a p53-responsive green fluorescent protein reporter strategy to enable the identification of live cells containing p53 transcriptional transactivation activity. We demonstrate within the use of GFP fluorescence to monitor both endogenous and plasmid derived p53 biochemical and biological activity. Identifying live cells with p53 activity through GFP fluorescence will have wide application for both in vitro and in vivo studies of the p53 tumor suppressor protein.

Limits to human locomotor performance: phylogenetic origins and comparative perspectives

Studies of human exercise physiology have been conducted from a largely ahistorical perspective. This approach usefully elucidates proximate limits to locomotor performance, but ignores potential sources of biomechanical and physiological variation that derive from adaptation to ancestral environments. Phylogenetic reconstruction suggests that multiple hominoid lineages, including that leading to Homo sapiens, evolved in African highlands at altitudes of 1000–2000m. The evolution of human locomotor physiology therefore occurred under conditions of hypobaric hypoxia. In contrast to present-day humans running on treadmills or exercising in otherwise rectilinear trajectories, ancestral patterns of hominid locomotion probably involved intermittent knuckle-walking over variable terrain, occasional bouts of arboreality and an evolving capacity for bipedalism. All such factors represent potential axes of locomotor variation at present unstudied in extant hominoid taxa. As with humans, hummingbirds evolved in mid-montane contexts but pose an extreme contrast with respect to body size, locomotor mode and metabolic capacity. Substantial biomechanical and physiological challenges are associated with flight in hypobaria. Nonetheless, hummingbird lineages demonstrate a progressive invasion of higher elevations and a remarkable tolerance to hypoxia during hovering. Upregulation of aerobic capacity and parallel resistance to hypoxia may represent coupled evolutionary adaptations to flight under high-altitude conditions.

The evolutionary physiology of animal flight: paleobiological and present perspectives

Recent geophysical analyses suggest the presence of a late Paleozoic oxygen pulse beginning in the late Devonian and continuing through to the late Carboniferous. During this period, plant terrestrialization and global carbon deposition resulted in a dramatic increase in atmospheric oxygen levels, ultimately yielding concentrations potentially as high as 35% relative to the contemporary value of 21%. Such hyperoxia of the late Paleozoic atmosphere may have physiologically facilitated the initial evolution of insect flight metabolism. Widespread gigantism in late Paleozoic insects and other arthropods is also consistent with enhanced oxygen flux within diffusion-limited tracheal systems. Because total atmospheric pressure increases with increased oxygen partial pressure, concurrently hyperdense conditions would have augmented aerodynamic force production in early forms of flying insects. By the late Permian, evolution of decompositional microbial and fungal communities, together with disequilibrium in rates of carbon deposition, gradually reduced oxygen concentrations to values possibly as low as 15%. The disappearance of giant insects by the end of the Permian is consistent with extinction of these taxa for reasons of asphyxiation on a geological time scale. As with winged insects, the multiple historical origins of vertebrate flight in the late Jurassic and Cretaceous correlate temporally with periods of elevated atmospheric oxygen. Much discussion of flight performance in Archaeopteryx assumes a contemporary atmospheric composition. Elevated oxygen levels in the mid- to late Mesozoic would, however, have facilitated aerodynamic force production and enhanced muscle power output for ancestral birds, as well as for precursors to bats and pterosaurs.

P53 polymorphism in codon 72 and risk of human papillomavirus-induced cervical cancer: effect of inter-laboratory variation

An association between codon-72 p53 polymorphism and risk of human papillomavirus (HPV)-induced cervical cancer has been found recently, but it has been difficult to replicate. In this study, we assess the impact of inter-laboratory variation in p53 genotyping on the validity of the proposed association. DNA specimens were randomly selected from 54 invasive, squamous cell carcinoma cases, 52 HPV-negative, and 39 HPV-positive controls from a previous case-control study in Brazil. Codon-72 polymorphism was blindly analyzed in three different laboratories. We calculated age- and race-adjusted odds ratios (OR) and 95% confidence intervals (CI) using logistic regression for gauging the association between p53 polymorphism and cervical cancer risk. The proportions of the Arg/Arg, Arg/Pro, and Pro/Pro genotypes varied substantially among laboratories with Kappa coefficients in the 0.49-0.63 range. When disagreement between labs was allowed, the OR for the Arg/Arg genotype, compared to other forms, was as low as 1.5 (95% CI: 0.5-3. 9). In contrast, the OR increased to 8.0 (95% CI: 2.3-28.5) after exclusion of discordant genotypes. Restricting the comparison to HPV-positive controls increased the magnitude of the relation appreciably. After exclusion of all discordant diagnoses, the OR was 21.5 (95% CI: 3.4-137.8), whereas with disagreed genotypes the association was not significant (OR = 2.9, 95% CI: 0.7-11.9). Homozygous codon-72 p53-Arg apparently confers a higher susceptibility to HPV-associated cervical tumorigenesis. However, exposure misclassification consequent to inter-laboratory variation in protocols may affect the ability to detect the association.

Evolutionary origins of human alcoholism in primate frugivory

Evolutionary origins of alcohol consumption have rarely been considered in studies of ethanol addiction. However, the occurrence of ethanol in ripe and decaying fruit and the substantial heritability of alcoholism in humans suggest an important historical association between primate frugivory and alcohol consumption. Olfactory localization of ripe fruit via volatilized alcohols, the use of ethanol as an appetitive stimulant, and the consumption of fruits with substantial ethanol content potentially characterize all frugivorous primates, including hominoids and the lineage leading to modern humans. Patterns of alcohol use by humans in contemporary environments may thus reflect a maladaptive co-option of ancestral nutritional strategies. Although diverse factors contribute to the expression of alcoholism as a clinical syndrome, historical selection for the consumption of ethanol in the course of frugivory can be viewed as a subtle yet pervasive evolutionary influence on modern humans.

Evidence for phosphorylation-dependent internalization of recombinant human rho1 GABAC receptors

1. Recombinant wild-type or mutant human rho1 GABA receptors were expressed in human embryonic kidney (HEK) 293 or monkey COS-7 cells and studied using the patch clamp technique. 2. Standard whole-cell recordings with 4 mM Mg-ATP in the patch pipette induced a time-dependent decrease in the GABA-activated current (IGABA) amplitude that was not the result of a decrease in GABA sensitivity. In contrast, IGABA remained stable when recordings were obtained using the perforated patch configuration or with standard whole-cell recording and no Mg-ATP in the patch pipette. 3. The inhibitors of serine/threonine protein kinases KN-62 (20 microM) or staurosporine (20 nM) prevented the time-dependent decrease in the amplitude of IGABA seen in the presence of ATP. Alkaline phosphatase (220 U ml-1), when added to the patch pipette in the absence of ATP, induced a transient potentiation of IGABA. Although the protein kinase C (PKC) activator 4beta-phorbol 12-myristate, 13-acetate (PMA) did not reduce the amplitude of IGABA, inclusion of the catalytic domain of PKC in the recording pipette accelerated the time-dependent decrease in current amplitude. These data suggest that phosphorylation is involved in the regulation of the amplitude of IGABA. 4. Mutation of the three PKC consensus sequences of the rho1 receptor had no significant effect on the decline in IGABA, indicating that direct phosphorylation of these putative sites on the rho1 receptor does not underlie the time-dependent decrease in amplitude. 5. In COS-7 cells transfected with wild-type rho1 receptors, the amplitude of IGABA had completely recovered to the original value when the same cells were repatched after 30-40 min, indicating that the decline in IGABA was a reversible process. 6. The inhibitor of actin filament formation cytochalasin B, when added to the patch pipette in the absence of ATP, induced a time-dependent inactivation suggesting that the actin cytoskeleton may play a role in the regulation of the amplitude. 7. Coincident with the decrease in the amplitude of IGABA, the cell capacitance significantly decreased in the presence of ATP in the patch pipette. This decrease in capacitance was not observed in the absence of Mg-ATP. The decrease in the membrane surface area suggests that receptor internalization could be a potential mechanism for the observed inactivation. 8. At 32 C, compared with 22 C, the rate and magnitude of the decline was increased dramatically. In contrast, at 16 C, no significant change in IGABA was observed over the 20 min recording time. This marked temperature sensitivity is consistent with receptor internalization as a mechanism for the time-dependent decline in IGABA. 9. The specificity of the decrease in IGABA was assessed by coexpressing the voltage-dependent potassium channel Kv1.4 along with the rho1 receptor in HEK293 cells. The amplitude of the potassium current (IKv1.4) exhibited very little decrement in comparison to IGABA suggesting that the putative GABA receptor internalization was not the consequence of a non-specific membrane retrieval.

Do neotropical migrant butterflies navigate using a solar compass?

Many tropical butterfly species are well-known for their migratory behaviour. Although these insects can maintain a constant direction throughout the day, the physiological mechanisms of orientation are unknown. It has been argued that tropical migrant butterflies must use a time-compensated sun compass to accomplish their journey, but the crucial experimental manipulations to test this hypothesis have not been conducted. This study reports the results of clock-shift experiments performed with two species of migrating butterflies (Pieridae: Aphrissa statira and Phoebis argante) captured during flight across Lake Gatun, Panama. The observed constant flight bearing of natural controls suggests that these species are capable of performing time-compensated celestial navigation. Our clock-shift experiments suggest that a sun compass is involved. Individuals submitted to a 4 h advance shift took significantly different mean orientations on release compared with control butterflies. The direction of this difference was consistent with the use of a sun compass. The magnitude was approximately half the predicted value if the vanishing bearing of released butterflies was used as the variable to evaluate the effect of time-shifting and approximately three-quarters of that predicted if the estimated heading was the variable used. Mean vanishing bearings of control and experimental butterflies did not correspond to predicted values. This difference can be attributed largely to the combined effects of wind and handling.

Atmospheric oxygen, giant Paleozoic insects and the evolution of aerial locomotor performance

Uniformitarian approaches to the evolution of terrestrial locomotor physiology and animal flight performance have generally presupposed the constancy of atmospheric composition. Recent geophysical data as well as theoretical models suggest that, to the contrary, both oxygen and carbon dioxide concentrations have changed dramatically during defining periods of metazoan evolution. Hyperoxia in the late Paleozoic atmosphere may have physiologically enhanced the initial evolution of tetrapod locomotor energetics; a concurrently hyperdense atmosphere would have augmented aerodynamic force production in early flying insects. Multiple historical origins of vertebrate flight also correlate temporally with geological periods of increased oxygen concentration and atmospheric density. Arthropod as well as amphibian gigantism appear to have been facilitated by a hyperoxic Carboniferous atmosphere and were subsequently eliminated by a late Permian transition to hypoxia. For extant organisms, the transient, chronic and ontogenetic effects of exposure to hyperoxic gas mixtures are poorly understood relative to contemporary understanding of the physiology of oxygen deprivation. Experimentally, the biomechanical and physiological effects of hyperoxia on animal flight performance can be decoupled through the use of gas mixtures that vary in density and oxygen concentration. Such manipulations permit both paleophysiological simulation of ancestral locomotor performance and an analysis of maximal flight capacity in extant forms.

Elastic structures in the vocalization apparatus of the Túngara frog Physalaemus pustulosus (Leptodactylidae)

Histological analysis of the vocal sac and body wall in the leptodactylid frog Physalaemus pustulosus suggests that both muscle and elastic fibers are important in call production. Abdominal musculature as well as abdominal bands of elastin (the lineae masculinae) provide the energy required for exhalation and sound production. Air flowing through the larynx inflates a highly extensible vocal sac lined with muscle and a network of elastic fibers. Inherent elasticity together with muscular activity of the vocal sac likely increase the speed and possibly decrease the energetic costs of lung reinflation following vocalization. The mechanics of call production in P. pustulosus thus involve not only laryngeal activation but also elastic transfer of air between the supralaryngeal vocal sac and abdominal respiratory structures.

Transient hovering performance of hummingbirds under conditions of maximal loading

Maximal load-lifting capacities of six ruby-throated hummingbirds (Archilochus colubris) were determined under conditions of burst performance. Mechanical power output under maximal loading was then compared with maximal hovering performance in hypodense gas mixtures of normodense air and heliox. The maximal load lifted was similar at air temperatures of 5 and 25 degrees C, and averaged 80% of body mass. The duration of load-lifting was brief, of the order of 1 s, and was probably sustained via phosphagen substrates. Under maximal loading, estimates of muscle mass-specific mechanical power output assuming perfect elastic energy storage averaged 206 W kg-1, compared with 94 W kg-1 during free hovering without loading. Under conditions of limiting performance in hypodense mixtures, maximal mechanical power output was much lower (131 W kg-1, five birds) but was sustained for longer (4 s), demonstrating an inverse relationship between the magnitude and duration of maximum power output. In free hovering flight, stroke amplitude and wingbeat frequency varied in inverse proportion between 5 and 25 degrees C, suggesting thermoregulatory contributions by the flight muscles. Stroke amplitude under conditions of maximal loading reached a geometrical limit at slightly greater than 180 degrees. Previous studies of maximum performance in flying animals have estimated mechanical power output using a simplified actuator disk model without a detailed knowledge of wingbeat frequency and stroke amplitude. The present load-lifting results, together with actuator disc estimates of induced power derived from hypodense heliox experiments, are congruent with previous load-lifting studies of maximum flight performance. For ruby-throated hummingbirds, the inclusion of wingbeat frequency and stroke amplitude in a more detailed aerodynamic model of hovering yields values of mechanical power output 34% higher than previous estimates. More generally, the study of performance limits in flying animals necessitates careful specification of behavioral context as well as quantitative determination of wing and body kinematics.

Oxandrolone in AIDS-wasting myopathy

OBJECTIVE

To evaluate oxandrolone, an oral anabolic steroid with potent anabolic activity and minimal androgenic effects, for the treatment of AIDS-associated myopathy and wasting.

METHODS

In a multicenter, double-blind study, 63 HIV-seropositive men with > 10% loss of body weight were randomized to receive either placebo, 5 mg/day oxandrolone, or 15 mg/day oxandrolone for 16 weeks. Body weight, neuromuscular evaluation, and measures of well-being were repeatedly assessed.

RESULTS

Patients who received 15 mg/day oxandrolone showed weight gain throughout the 16-week treatment period. Overall, the 5 mg/day oxandrolone group maintained their weight gain over the 16-week period, whereas the placebo group showed continual weight loss. At week 16, significantly more patients in the 15 mg/day dose group reported increases in appetite and activity than those receiving placebo. There were no consistent, dose-related, statistically significant differences from baseline in laboratory values or adverse events.

CONCLUSION

Oxandrolone, at a dose of either 5 mg/day or 15 mg/day, in contrast to placebo, had a positive impact on the weight and well-being of HIV-seropositive patients suffering from wasting and weakness. Measurable improvement in muscle strength was not noted at the doses employed in this study. Oxandrolone was well tolerated in all the patients who were enrolled in the study. Based on the results reported here, additional studies using higher doses of oxandrolone seem warranted.

Hummingbird hovering performance in hyperoxic heliox: effects of body mass and sex

Owing to their small size and hovering locomotion, hummingbirds are the most aerobically active vertebrate endotherms. Can hyperoxia enhance the flight performance of this highly oxygen-dependent group? Hovering performance of ruby-throated hummingbirds (Archilochus colubris) was manipulated non-invasively using hyperoxic but hypodense gas mixtures of sea-level air combined with heliox containing 35% O2. This manipulation sheds light on the interplay among metabolic power input, mechanical power output and aerodynamic force production in limiting flight performance. No significant differences in flight mechanics and oxygen consumption were identified between hyperoxic and normoxic conditions. Thus, at least in the present experimental context, hyperoxia did not change the major metabolic and mechanical parameters; O2 diffusive capacities of the respiratory system were probably not limiting to a significant extent. Compared with hummingbirds in our previous studies, the present experimental birds were heavier, had resultant shorter hover-feeding durations and experienced aerodynamic failure at higher air densities. Because hummingbirds have relatively stable wingbeat frequencies, modulation of power output was attained primarily through variation in stroke amplitude up to near 180 degrees. This result indicates that maximum hovering performance was constrained geometrically and that heavier birds with greater fat loads had less margin for enhancement of power production. Sexual dimorphism in flight adaptation also played a role, with males showing more limited hovering capacities, presumably as a trade-off for increased maneuverability.

Limits to flight energetics of hummingbirds hovering in hypodense and hypoxic gas mixtures

Hovering hummingbirds offer a model locomotor system for which analyses of both metabolism and flight mechanics are experimentally tractable. Because hummingbirds exhibit the highest mass-specific metabolic rates among vertebrates, maximum performance of hovering flight represents the upper limit of aerobic locomotion in vertebrates. This study evaluates the potential constraints of flight mechanics and oxygen availability on maximum flight performance. Hummingbird flight performance was manipulated non-invasively using air and gas mixtures which influenced metabolism via variable oxygen partial pressure and/or altered flight mechanics via variable air densities. Limits to the locomotor capacity of hovering ruby-throated hummingbirds (Archilochus colubris) were unequivocally indicated by aerodynamic failure in either air/helium or air/heliox mixtures. Air/helium mixtures are hypodense and hypoxic; failure to sustain hovering flight occurred at 63% of the density of sea-level air and at an oxygen concentration of 12%. Air/heliox mixtures are hypodense but normoxic; failure in hovering occurred at 47% of sea-level air density. Thus, hummingbirds demonstrated considerable power reserves in hovering flight as well as hypoxic tolerance. In air/helium mixtures, hovering was limited by oxygen supply and not by flight mechanics. Birds hovering in air/helium mixtures increased their mechanical power output but not their rate of oxygen consumption. By contrast, birds hovering in air/heliox mixtures increased both mechanical performance and metabolic expenditure. Under hypoxia, hovering hummingbirds demonstrated non-negligible, but still limited, capacities for anaerobic metabolism and/or oxygen storage. Depending on the physical context, hummingbird flight performance can therefore be limited by oxygen availability or by flight aerodynamics.

Animal flight mechanics in physically variable gas mixtures

Empirical studies of animal flight performance have generally been implemented within the contemporary atmosphere. Experimental alteration of the physical composition of gas mixtures, however, permits construction of novel flight media and the non-invasive manipulation of flight biomechanics. For example, replacement of atmospheric nitrogen with various noble gases results in a tenfold variation in air density at a constant oxygen concentration. Such variation in air density correspondingly elicits extraordinary biomechanical effort from flying animals; hummingbirds and euglossine orchid bees hovering in such low-density but normoxic mixtures have demonstrated exceptionally high values for the mechanical power output of aerobic flight muscle. As with mechanical power, lift coefficients during hovering increase at low air densities in spite of a concomitant decline in the Reynolds number of the wings. The physical effects of variable gas density may also be manifest in morphological and physiological adaptations of animals to flight across altitudinal gradients. Global variation in atmospheric composition during the late Paleozoic may also have influenced the initial evolution and subsequent diversification of ancestral pterygotes. For the present-day experimenter, the use of physically variable flight media represents a versatile opportunity to explore the range of kinematic and aerodynamic modulation available to flying animals.

Oxandrolone therapy in constitutionally delayed growth and puberty. Bio-Technology General Corporation Cooperative Study Group

BACKGROUND

Male adolescents with constitutional delay of growth and puberty may have significant psychosocial difficulties related to their sexual immaturity and short stature. The purpose of this study was to test the hypothesis that 1 year of oxandrolone therapy would increase growth velocity and thereby improve psychosocial functioning in boys with constitutional delay of growth and pubertal development.

METHODS

Forty boys (ages 11 to 14.7 years) with delayed pubertal development and short stature were recruited from the pediatric endocrine clinics of 14 medical centers. The boys were randomized using a block design stratified for age to receive either oxandrolone (0.1 mg/kg daily for 1 year) or an identical-appearing placebo tablet, using a double-masked design.

RESULTS

Growth velocity in the oxandrolone-treated boys was significantly greater than in the control boys (9.5 vs 6.8 cm/y). Likewise, the mean height SD score increased 0.41 in the oxandrolone group, whereas it decreased 0.03 in the control group. Those in the oxandrolone group gained 2.4 kg more than those in the placebo group. Mean predicted adult heights did not change in either group. The mean rates of pubertal progression were equivalent in both groups. Self-image (Piers-Harris Self Concept Scale) and social competence (Child Behavior Profile) were normal at baseline in both groups and did not change significantly over the course of the study in either group. No complications of oxandrolone therapy were identified.

CONCLUSIONS

This randomized, placebo-controlled trial demonstrates that low-dose oxandrolone can increase both height and weight velocity in boys with delayed puberty safely. Under the conditions of this study, however, the increased growth velocity in the oxandrolone-treated boys was not associated with a greater improvement in psychosocial status compared with the control boys.

Rebound severe methemoglobinemia from ingestion of a nitroethane artificial-fingernail remover

We describe life-threatening methemoglobinemia in a child who ingested a nitroethane artificial-fingernail remover initially mistaken to be an acetone-based polish remover. Nitroethane-induced methemoglobinemia may be delayed and recurrent; patients ingesting this substance may warrant close observation for at least 24 hours. Care givers are cautioned to determine the precise substance involved in ingestions of potentially toxic fingernail products.