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Biomedical subjects

John Hunt

Publications and source records attributed to John Hunt.

At least 19 recordsLinked to original sources
PubMed2005

Comparisons of NMR spectral quality and success in crystallization demonstrate that NMR and X-ray crystallography are complementary methods for small protein structure determination.

X-ray crystallography and NMR spectroscopy provide the only sources of experimental data from which protein structures can be analyzed at high or even atomic resolution. The degree to which these methods complement each other as sources of structural knowledge is a matter of debate; it is often proposed that small proteins yielding high quality, readily analyzed NMR spectra are a subset of those that readily yield strongly diffracting crystals. We have examined the correlation between NMR spectral quality and success in structure determination by X-ray crystallography for 159 prokaryotic and eukaryotic proteins, prescreened to avoid proteins providing polydisperse and/or aggregated samples. This study demonstrates that, across this protein sample set, the quality of a protein's [15N-1H]-heteronuclear correlation (HSQC) spectrum recorded under conditions generally suitable for 3D structure determination by NMR, a key predictor of the ability to determine a structure by NMR, is not correlated with successful crystallization and structure determination by X-ray crystallography. These results, together with similar results of an independent study presented in the accompanying paper (Yee, et al., J. Am. Chem. Soc., accompanying paper), demonstrate that X-ray crystallography and NMR often provide complementary sources of structural data and that both methods are required in order to optimize success for as many targets as possible in large-scale structural proteomics efforts.

Animals↗
PubMed2005

Assaying all of the nitrogen oxides in breath modifies the interpretation of exhaled nitric oxide.

Exhaled nitric oxide (NO) assays measure the quantity of NO that emanates from the airway, not the amount of NO that is formed. Consumptive processes-including oxidation reactions-decrease the amount of gas phase NO available for exhalation. Higher oxides of nitrogen (HiNO(x)) are resulting reaction products, and are easily measured in exhaled breath condensate (EBC). We performed concurrent sampling of exhaled breath for gas phase NO and EBC HiNO(x) in controls and stable asthmatics. We identified that, mole for mole, asthma patients hourly exhale more HiNO(x) than they do NO, with a HiNO(x)/NO ratio of 1.21 (0.54-3.4). This is the reverse of the ratio found in controls, in whom the HiNO(x)/NO ratio was 0.75 (0.44-0.93), p=0.04. The sum of the hourly molar exhalation of NO and HiNO(x) was significantly higher in asthmatics (333 nmol/h (221-543) than controls (179 (138-231), p<0.001). We conclude that exhaled oxides of nitrogen are more informative when measured together as opposed to in isolation. We suggest that inflammation can be better evaluated with HiNO(x) and NO measured concurrently, and that the level of oxidation in the lung can be evaluated by comparing the easily measured ratios of HiNO(x) to NO in the exhaled breath.

Adolescent↗
PubMed2005

Female mate choice as a condition-dependent life-history trait.

The acquisition of resources is an important determinant of patterns of variation in and covariation among traits that are costly to produce and are dependent on condition for their expression. However, the extent to which variation in female mate choice behavior is condition dependent, and how this is related to other life-history traits, remains largely unknown. We manipulated the acquisition of dietary protein in the black field cricket, Teleogryllus commodus, and measured the effects of this on several important life-history traits and on female mate choice behavior. Females reared on a high-protein diet developed faster, were heavier at eclosion, and lived longer than females reared on a low-protein diet. Two lines of evidence suggest that female mate choice behavior in T. commodus is condition dependent. First, females reared on the high-protein diet were more sexually responsive and expressed stronger linear and quadratic preference functions for call rate and dominant frequency, respectively. Second, within treatments, females that developed faster were lighter, generally less sexually responsive, and, in the high-protein-diet treatment, expressed weaker preferences than slower-developing females. Collectively, our findings suggest an important role for resource acquisition in generating variation in mate choice behavior.

Animals↗
PubMed2005

Application of genome-wide expression analysis to human health and disease.

The application of genome-wide expression analysis to a large-scale, multicentered program in critically ill patients poses a number of theoretical and technical challenges. We describe here an analytical and organizational approach to a systematic evaluation of the variance associated with genome-wide expression analysis specifically tailored to study human disease. We analyzed sources of variance in genome-wide expression analyses performed with commercial oligonucleotide arrays. In addition, variance in gene expression in human blood leukocytes caused by repeated sampling in the same subject, among different healthy subjects, among different leukocyte subpopulations, and the effect of traumatic injury, were also explored. We report that analytical variance caused by sample processing was acceptably small. Blood leukocyte gene expression in the same individual over a 24-h period was remarkably constant. In contrast, genome-wide expression varied significantly among different subjects and leukocyte subpopulations. Expectedly, traumatic injury induced dramatic changes in apparent gene expression that were greater in magnitude than the analytical noise and interindividual variance. We demonstrate that the development of a nation-wide program for gene expression analysis with careful attention to analytical details can reduce the variance in the clinical setting to a level where patterns of gene expression are informative among different healthy human subjects, and can be studied with confidence in human disease.

Cluster Analysis↗
PubMed2005

The indirect benefits of mating with attractive males outweigh the direct costs.

The fitness consequences of mate choice are a source of ongoing debate in evolutionary biology. Recent theory predicts that indirect benefits of female choice due to offspring inheriting superior genes are likely to be negated when there are direct costs associated with choice, including any costs of mating with attractive males. To estimate the fitness consequences of mating with males of varying attractiveness, we housed female house crickets, Acheta domesticus, with either attractive or unattractive males and measured a variety of direct and indirect fitness components. These fitness components were combined to give relative estimates of the number of grandchildren produced and the intrinsic rate of increase (relative net fitness). We found that females mated to attractive males incur a substantial survival cost. However, these costs are cancelled out and may be outweighed by the benefits of having offspring with elevated fitness. This benefit is due predominantly, but not exclusively, to the effect of an increase in sons' attractiveness. Our results suggest that the direct costs that females experience when mating with attractive males can be outweighed by indirect benefits. They also reveal the value of estimating the net fitness consequences of a mating strategy by including measures of offspring quality in estimates of fitness.

Animals↗
PubMed2005

Chronic hyperplastic eosinophilic sinusitis as a predictor of aspirin-exacerbated respiratory disease.

BACKGROUND: Aspirin-exacerbated respiratory disease (AERD) is a disease of intense eosinophilic inflammation that can produce fibrosis, hyperplasia, and remodeling. OBJECTIVE: To investigate the usefulness of quantifying severity of chronic hyperplastic eosinophilic sinusitis in predicting the presence of AERD. METHODS: Data were compared between asthmatic patients who reported exacerbations after aspirin ingestion and those who did not. The primary outcome measure was severity of sinusitis using a validated computed tomography (CT) scan-based scoring system. Indices of lower airway remodeling and other markers of inflammation were also evaluated. RESULTS: Twenty-one patients with AERD were compared with 19 patients with aspirin-tolerant asthma (ATA). Patients were well matched for asthma severity as shown by their similar lung function as measured by postbronchodilator forced expiratory volume in 1 second. Patients with AERD were distinguished by their sinus CT scores (AERD patients: 16.9; 95% confidence interval [CI], 13.4-21.3; ATA patients: 6.2; 95% CI, 4.2-9.1; P < .001), and they were considerably more likely to have nasal polyps (AERD patients: 90%; ATA patients: 26%; P < .001). In addition, AERD patients demonstrated increased total lung capacity (AERD patients: 107.9%; 95% CI, 99.9%-117.6%; ATA patients: 98.0%; 95% CI, 93.7%-102.5%; P = .05), reflecting a trend toward increased air trapping. No significant differences occurred in diffusing capacity, exhaled nitric oxide, eosinophilia, or exhaled breath condensate pH. CONCLUSIONS: AERD can be distinguished from ATA by the extent of hyperplasia on CT scan and the presence of nasal polyps. We hypothesize that AERD represents a remodeling process that affects both the upper and lower airways.

Adult↗
PubMed2005

Evolution of sexual dimorphism and male dimorphism in the expression of beetle horns: phylogenetic evidence for modularity, evolutionary lability, and constraint.

Beetle horns are enlarged outgrowths of the head or thorax that are used as weapons in contests over access to mates. Horn development is typically confined to males (sexual dimorphism) and often only to the largest males (male dimorphism). Both types of dimorphism result from endocrine threshold mechanisms that coordinate cell proliferation near the end of the larval period. Here, we map the presence/absence of each type of dimorphism onto a recent phylogeny for the genus Onthophagus (Coleoptera: Scarabaeidae) to explore how horn development has changed over time. Our results provide empirical support for several recent predictions regarding the evolutionary lability of developmental thresholds, including uncoupled evolution of alternative phenotypes and repeated fixation of phenotypes. We also report striking evidence of a possible developmental constraint. We show that male dimorphism and sexual dimorphism map together on the phylogeny; whenever small males have horns, females also have horns (and vice versa). We raise the possibility that correlated evolution of these two phenomena results from a shared element in their endocrine regulatory mechanisms rather than a history of common selection pressures. These results illustrate the type of insight that can be gained only from the integration of developmental and evolutionary perspectives.

Animals↗
PubMed2005

Experimental evidence for multivariate stabilizing sexual selection.

Stabilizing selection is a fundamental concept in evolutionary biology. In the presence of a single intermediate optimum phenotype (fitness peak) on the fitness surface, stabilizing selection should cause the population to evolve toward such a peak. This prediction has seldom been tested, particularly for suites of correlated traits. The lack of tests for an evolutionary match between population means and adaptive peaks may be due, at least in part, to problems associated with empirically detecting multivariate stabilizing selection and with testing whether population means are at the peak of multivariate fitness surfaces. Here we show how canonical analysis of the fitness surface, combined with the estimation of confidence regions for stationary points on quadratic response surfaces, may be used to define multivariate stabilizing selection on a suite of traits and to establish whether natural populations reside on the multivariate peak. We manufactured artificial advertisement calls of the male cricket Teleogryllus commodus and played them back to females in laboratory phonotaxis trials to estimate the linear and nonlinear sexual selection that female phonotactic choice imposes on male call structure. Significant nonlinear selection on the major axes of the fitness surface was convex in nature and displayed an intermediate optimum, indicating multivariate stabilizing selection. The mean phenotypes of four independent samples of males, from the same population as the females used in phonotaxis trials, were within the 95% confidence region for the fitness peak. These experiments indicate that stabilizing sexual selection may play an important role in the evolution of male call properties in natural populations of T. commodus.

Analysis of Variance↗
PubMed2004

High-quality male field crickets invest heavily in sexual display but die young.

Only high-quality males can bear the costs of an extreme sexual display. As a consequence, such males are not only more attractive, but they often live longer than average. Recent theory predicts, however, that high-quality males should sometimes invest so heavily in sexual displays that they die sooner than lower quality males. We manipulated the phenotypic quality of field crickets, Teleogryllus commodus, by altering the protein content of their diet. Here we show that nymphs and adult females reared on a high-protein diet lived longer than those on a low-protein diet. In contrast, adult males reared on a high-protein diet died sooner than those on low-protein diets because they invested more energy in calling during early adulthood. Our findings uphold the theoretical prediction that the relationship between longevity and sexual advertisement may be dynamic (that is, either positive or negative), depending on local conditions such as resource availability. Moreover, they caution the use of longevity as a proxy for fitness in sexual selection studies, and suggest avenues for future research on the relationship between sexual attractiveness and ageing.

Aging↗
PubMed2004

The mother-in-law effect.

Individuals often derive considerable evolutionary benefit from manipulating others. In the majority of cases, manipulation involves direct interactions between individuals. In the dung beetle, Onthophagus taurus, females mated with large males provide more resources to their offspring. Here, we demonstrate, however, that this may result in manipulation that extends across generations: the care that a mother provides to a developing son influences the parental effort of his mate (the mother's daughter-in-law (DIL)). Maternal care associated with constructing heavier brood masses has previously been shown substantially to influence offspring size, male mating success and female survival and fecundity in this species. The mother-in-law effect that we document here is, however, the ability to produce large sons from relatively lighter brood masses. Our results demonstrate not only that females are able to manipulate the parental effort of DILs that they do not directly encounter, but that provisioning relatively lighter brood masses may have evolutionary benefits that trade off against the considerable benefits of producing heavy brood masses.

Animals↗
PubMed2004

Sinister strategies succeed at the cricket World Cup.

Left-handers occur at unexpectedly high frequencies at top levels of many interactive sports. This may occur either because left-handed contestants are innately superior or because they enjoy a negatively frequency-dependent strategic advantage when rare relative to right-handers. We analysed the batting records from the 2003 cricket World Cup and showed that left-handed batsmen were more successful than right-handers, and that the most successful teams had close to 50% left-handed batsmen. We demonstrate that this was because left-handed batsmen have a strategic advantage over bowlers, and that this advantage is greatest over bowlers that are unaccustomed to bowling to left-handers. This provides a clear mechanism for negative frequency-dependent success of left-handed batsmen. Our results may also support a historical role for negative frequency-dependent success in fights and other contests in the maintenance of left-handedness by natural selection.

Functional Laterality↗
PubMed2004

Acid stress in the pathology of asthma.

Although alteration of airway pH may serve an innate host defense capacity, it also is implicated in the pathophysiology of obstructive airway diseases. Acid-induced asthma appears in association with gastroesophageal reflux after accidental inhalation of acid (fog, pollution, and workplace exposure) and in the presence of altered airway pH homeostasis. Endogenous and exogenous exposures to acids evoke cough, bronchoconstriction, airway hyperreactivity, microvascular leakage, and heightened production of mucous, fluid, and nitric oxide. Abnormal acidity of the airways is reflected in exhaled breath assays. The intimate mechanisms of acid-induced airway obstruction are dependent on activation of capsaicin-sensitive sensory nerves. Protons activate these nerves with the subsequent release of tachykinins (major mediators of this pathway) that, in conjunction with kinins, nitric oxide, oxygen radicals, and proteases, modulate diverse aspects of airway dysfunction and inflammation. The recognition that acid stress might initiate or exacerbate airway obstructive symptomatology has prompted the consideration of new therapies targeting pH homeostasis.

Acids↗
PubMed2004

No evidence for inbreeding avoidance through postcopulatory mechanisms in the black field cricket, Teleogryllus commodus.

Several studies suggest that females mate multiply so that they can preferentially fertilize eggs with the sperm of genetically more compatible males. Unrelated males are expected to be genetically more compatible with a female than her close relatives. We tested whether black field crickets, Teleogryllus commodus, can bias sperm usage toward unrelated males by comparing egg hatching success of females mated to two of their siblings (SS), two sibling males unrelated to the female (NN) or to one unrelated male and a sibling male (NS or SN). Egg hatching success was highly repeatable. Hatching success varied significantly among females of the three mating types (P = 0.011, n = 245 females). The estimated mean hatching success of 36.8% for SS females was significantly less that the 43.4% of NN females, indicating an effect of inbreeding on hatching success. If females preferentially use the sperm of a less closely related male, the hatching success of NS/SN females should be closer to 43.4% than 36.8%. It was, in fact, only 34.9%. This does not differ significantly from the value expected if the two males contributed an equal amount of sperm that was then used randomly. Although polyandry may confer indirect genetic benefits, our results provide no evidence that female T. commodus gain these benefits by biasing paternity toward genetically more compatible males through postcopulatory mechanisms.

Animals↗
PubMed2003

Selective dendrite-targeting of mRNAs of NR1 splice variants without exon 5: identification of a cis-acting sequence and isolation of sequence-binding proteins.

Both protein and mRNA for the NR1 subunit of N-methyl-D-aspartate receptors are present in neuronal dendrites and undergo changes in distribution following synaptic excitation. However, the expression of all exonic splice variants of NR1 in dendrites has not been determined. In the present study, antibodies against the exon 5 (ex5) peptide sequence labeled proteins mostly in the soma of hippocampus neurons, whereas antibodies against ex21 or ex22 labeled cell bodies and dendrites. Antisense cRNAs for ex5 hybridized with mRNAs in cell bodies, whereas cRNAs for ex21 with mRNAs in both cell bodies and dendrites. Antisense DNA to a 24-base sequence identified as being present only in the 5'-UTR of cDNAs lacking ex5 (ex5(-)), hybridized with mRNAs in soma and dendrites and this labeling was coincident, mostly, with RNA granules. Insertion of the 24-base DNA ahead of that for enhanced green fluorescent protein (EGFP) increased the transport of EGFP mRNA and the expression of EGFP in neurites of neurons in culture. Fluorescent sense mRNA that contained the 24-base sequence bound to proteins in dendrites and to two proteins, 60 and 70 kDa, in brain microsomes. Proteins of similar size were also labeled by [32P]CTP-mRNA for NR1-(1a), which contains the 24-base 5'-UTR sequence, but not for NR1-(2b), which does not. Biotinylated 24-base sense mRNA was used to purify from brain microsomes two RNA-binding proteins (60 and 70 kDa). We concluded that the 24-base sequence in 5'-UTR of ex5(-) mRNA functioned as a cis-acting, dendrite-targeting element recognized selectively by two microsome proteins.

Animals↗
PubMed2003

Males influence maternal effects that promote sexual selection: a quantitative genetic experiment with dung beetles Onthophagus taurus.

Recently, doubt has been cast on studies supporting good genes sexual selection by the suggestion that observed genetic benefits for offspring may be confounded by differential maternal allocation. In traditional analyses, observed genetic sire effects on offspring phenotype may result from females allocating more resources to the offspring of attractive males. However, maternal effects such as differential allocation may represent a mechanism promoting genetic sire effects, rather than an alternative to them. Here we report results from an experiment on the horned dung beetle Onthophagus taurus, in which we directly compare genetic sire effects with maternal effects that are dependent on sire phenotype. We found strong evidence that mothers provide more resources to offspring when mated with large-horned males. There were significant heritabilities for both horn length and body size, but when differential maternal effects were controlled, the observed estimates of genetic variance were greatly reduced. Our experiment provides evidence that differential maternal effects may amplify genetic effects on offspring traits that are closely related to fitness. Thus, our results may partly explain the relatively high coefficients of additive genetic variation observed in fitness-related traits and provide empirical support for the theoretical argument that maternal effects can play an important role in evolution.

Animals↗
PubMed2003

Overcoming the challenges to consumer involvement in cancer research.

INTRODUCTION: Within the last decade, there have been many government initiatives to promote consumer involvement in research, especially in cancer. At the same time, the number and influence of consumer groups themselves have expanded. However, the organizational infrastructure necessary to facilitate consumer involvement has not been developed. Consequently, consumer involvement has tended to remain essentially localized and project driven, with no strategic or regional lead. OPPORTUNITIES FOR INVOLVEMENT AND IDENTIFICATION OF CONSUMERS: The opportunities for consumers to influence the research process at each stage of the research process are identified. The different types of consumer involvement are also examined. Novel ways of identifying and recruiting consumers that have been adopted by one cancer network are discussed. THE STRATEGIES USED IN ONE CANCER NETWORK: An organizational model designed by one cancer network for involving consumers in research is illustrated. Three innovations are examined in detail. First, how three open consumer conferences have increased awareness of research among service users. Second, the recruitment of consumers to sit on project steering groups and a committee that provides a strategic overview of current research. Third, the establishment of a Consumer Panel for Research where reimbursed, trained consumers are able to provide a considered consumer perspective in a range of settings. CONCLUSIONS: Cancer networks need to take the lead in the development of an organizational infrastructure to facilitate consumer involvement. The model developed in Sheffield could be generalizable to other diseases and other health-care settings.

Biomedical Research↗