Ecological opportunity and the origin of adaptive radiations

Ecological opportunity--through entry into a new environment, the origin of a key innovation or extinction of antagonists--is widely thought to link ecological population dynamics to evolutionary diversification. The population-level processes arising from ecological opportunity are well documented under the concept of ecological release. However, there is little consensus as to how these processes promote phenotypic diversification, rapid speciation and adaptive radiation. We propose that ecological opportunity could promote adaptive radiation by generating specific changes to the selective regimes acting on natural populations, both by relaxing effective stabilizing selection and by creating conditions that ultimately generate diversifying selection. We assess theoretical and empirical evidence for these effects of ecological opportunity and review emerging phylogenetic approaches that attempt to detect the signature of ecological opportunity across geological time. Finally, we evaluate the evidence for the evolutionary effects of ecological opportunity in the diversification of Caribbean Anolis lizards. Some of the processes that could link ecological opportunity to adaptive radiation are well documented, but others remain unsupported. We suggest that more study is required to characterize the form of natural selection acting on natural populations and to better describe the relationship between ecological opportunity and speciation rates.

The placebo effect and its determinants in osteoarthritis: meta-analysis of randomised controlled trials

OBJECTIVE

To examine the placebo effect and its potential determinants in the treatment of osteoarthritis (OA) via a systematic literature search of Medline, EMBASE, Scientific Citation Index, Cumulative Index to Nursing and Allied Health Literature (CINAHL) and Cochrane Library.

METHODS

Randomised placebo controlled trials in OA were included. The placebo effect was defined as the overall change from baseline in the placebo group. It was estimated as the effect size (ES; the standard mean difference between baseline and endpoint) and this was compared with the ES obtained from untreated control. ES for pain was the primary outcome. Statistical pooling was undertaken as appropriate and 95% CIs were used for comparison. Quality of trials was assessed and potential determinants of placebo effect were examined using multiple regression analysis. The partial regression coefficient (beta) was used to present the adjusted size of the association.

RESULTS

We identified 198 trials with 193 placebo groups (16 364 patients) and 14 untreated control groups (1167 patients) that met our inclusion criteria. These included a range of therapies (non-pharmacological, pharmacological and surgical treatments). Placebo was effective at relieving pain (ES 0.51, 95% CI 0.46 to 0.55 for the placebo group and 0.03, 95% CI -0.13 to 0.18 for untreated control). Placebo was also effective at improving function and stiffness. The pain-relieving effect increased when the active treatment effect (beta=0.38, p<0.001), baseline pain (0.006, p=0.014) and sample size (0.001, p=0.004) increased, and when placebo was given through injections/needles (0.144, p=0.020).

CONCLUSION

Placebo is effective in the treatment of OA, especially for pain, stiffness and self-reported function. The size of this effect is influenced by the strength of the active treatment, the baseline disease severity, the route of delivery and the sample size of the study.

Avian influenza A viruses differ from human viruses by recognition of sialyloligosaccharides and gangliosides and by a higher conservation of the HA receptor-binding site

Avian influenza virus strains representing most hemagglutinin (HA) subtypes were compared with human influenza A (H1N1,H3N2) and B virus isolates, including those with no history of passaging in embryonated hen's eggs, for their ability to bind free N-acetylneuraminic acid (Neu5Ac) and sialylollgosaccharides in a competitive binding assay and to attach to gangliosides in a solid-phase adsorption assay. The avian viruses, irrespective of their HA subtype, showed a higher affinity for sialyl-3-lactose and the other Neu5Ac2-3Gal-terminated oligosaccharides and a lower affinity for sialyl-6-lactose than for free Neu5Ac, indicative of specific interactions between the HA and the 3-linked Gal and poor accommodation of 6-linked Gal in the avian receptor-binding site (RBS). Human H1 and H3 strains, by contrast, were unable to bind to 3-linked Gal, interacting instead with the asialic portion of sialyl-6-(N-acetyllactosamine). Different parts of this moiety were recognized by H3 and H1 subtype viruses (Gal and GlcNAc, respectively). Comparison of the HA amino acid sequences revealed that residues in positions. 138, 190, 194, 225, 226, and 228 are conserved in the avian RBS, while the human HAs harbor substitutions at these positions. A characteristic feature of avian viruses was their binding to Neu5Ac2-3Gal-containing gangliosides. This property of avian precursor viruses was preserved in early human H3 isolates, but was gradually lost with further circulation of the H3 HA in humans. Consequently, later human H3 isolates, as well as H1 and type B human strains, were unable to bind to short Neu5Ac2-3Gal-terminated gangliosides, an incompatibility that correlated with higher glycosylation of the HA globular head of human viruses. Our results suggest that the RBS is highly conserved among HA subtypes of avian influenza virus, while that of human viruses displays distinctive genotypic and phenotypic variability.

Topical antimicrobial toxicity

Three topical antibiotics and four antiseptics (1% povidone-iodine, 0.25% acetic acid, 3% hydrogen peroxide, and 0.5% sodium hypochlorite) were directly applied to cultured human fibroblasts to quantitatively assess their cytotoxicity. The four antiseptics were found to be cytotoxic; all of the cytotoxic agents except hydrogen peroxide were subsequently found to adversely affect wound healing in an animal model. Comparison of bactericidal and cytotoxic effects of serial dilutions of these four topical agents indicated the cellular toxicity of hydrogen peroxide and acetic acid exceeded their bactericidal potency. Bactericidal noncytotoxic dilutions of povidone-iodine and sodium hypochlorite were identified. These experiments provide evidence that 1% povidone-iodine, 3% hydrogen peroxide, 0.5% sodium hypochlorite, and 0.25% acetic acid are unsuitable for use in wound care. This sequence of experiments could be used to identify bactericidal, noncytotoxic agents prior to their clinical use.

The receptor tyrosine kinase EphB2 regulates NMDA-dependent synaptic function

Members of the Eph family of receptor tyrosine kinases control many aspects of cellular interactions during development, including axon guidance. Here, we demonstrate that EphB2 also regulates postnatal synaptic function in the mammalian CNS. Mice lacking the EphB2 intracellular kinase domain showed wild-type levels of LTP, whereas mice lacking the entire EphB2 receptor had reduced LTP at hippocampal CA1 and dentate gyrus synapses. Synaptic NMDA-mediated current was reduced in dentate granule neurons in EphB2 null mice, as was synaptically localized NR1 as revealed by immunogold localization. Finally, we show that EphB2 is upregulated in hippocampal pyramidal neurons in vitro and in vivo by stimuli known to induce changes in synaptic structure. Together, these data demonstrate that EphB2 plays an important role in regulating synaptic function.

Utah Growth Study: growth standards and the prevalence of growth hormone deficiency

Serial measurements of elementary-school children were conducted for 2 consecutive years to assess height and growth velocity and to determine the prevalence of growth hormone deficiency (GHD) in American children. Trained volunteers measured 114,881 children the first year; 79,495 growth rates were calculated after the second measurements. The height and growth velocity curves generated were very similar to the currently used charts. We examined 555 children with short stature (< 3rd percentile) and poor growth rates (< 5 cm/yr). Five percent had an endocrine disorder. The presence of GHD (peak level, < 10 ng/dl with two provocative tests) was found in 16 previously unrecognized children; 17 children from this school population were already known to have GHD. Boys outnumbered girls 2.7:1 (p = 0.006). Six girls with Turner syndrome also were identified. We conclude that (1) the growth curves generated in the 1960s and 1970s are valid for children of the 1990s; (2) most children growing < 5 cm/yr (a commonly used threshold rate) will not have an endocrine disorder; (3) many children (48% in this study) with GHD and others with Turner syndrome may currently be unrecognized and untreated; (4) GHD appears to be more common in boys; and (5) the prevalence of GHD in the United States is at least 1:3480.

Response to a specific antioestrogen (ICI 182780) in tamoxifen-resistant breast cancer

We treated 19 patients with advanced breast cancer resistant to tamoxifen with a new specific antioestrogen (ICI 182780) which, in animal studies, has no agonist activity. 13 (69%) patients responded (7 had partial responses and 6 showed no change) to monthly intramuscular injections of ICI 182780 after progression on tamoxifen, for a median duration of 18 months with minimum side effects. Preliminary evidence suggests that the agent is without effects on the liver or the hypothalamic-pituitary axis. ICI 182780 appears to be a promising new agent for treatment of advanced and early breast cancer.

Kohn anomalies and electron-phonon interactions in graphite

We demonstrate that graphite phonon dispersions have two Kohn anomalies at the Gamma-E(2g) and K-A'1 modes. The anomalies are revealed by two sharp kinks. By an exact analytic derivation, we show that the slope of these kinks is proportional to the square of the electron-phonon coupling (EPC). Thus, we can directly measure the EPC from the experimental dispersions. The Gamma-E(2g) and K-A'1 EPCs are particularly large, while they are negligible for all the other modes at Gamma and K.

Efficacy of tricyclic drugs in treating child and adolescent depression: a meta-analysis

OBJECTIVE

To examine whether tricyclic antidepressants are superior to placebo in the treatment of child and adolescent depression.

DESIGN

Meta-analysis of 12 randomised controlled trials comparing the efficacy of tricyclic antidepressants with placebo in depressed subjects aged 6-18 years.

MAIN OUTCOME MEASURES

Most studies employed several depression rating scales. For each study the "best available" measure was chosen by using objective criteria, and individual and pooled effect sizes were calculated as the number of standard deviations by which the change scores for the treatment groups exceeded those for the control groups. Where authors had reported numbers "responding" to treatment we calculated individual and pooled ratios for the odds of improvement in treated compared with control subjects.

RESULTS

From the six studies presenting data which enabled an estimation of effect size the pooled effect size was 0.35 standard deviations (95% confidence interval of -0.16 to 0.86) indicating no significant benefit of treatment. From the five studies presenting data on the number of "responders" in each group, the ratio of the odds of a response in the treated compared with the control subjects was calculated and the pooled odds ratio was 1.08 (95% confidence interval of 0.53 to 2.17); again indicating no significant benefit of treatment. The pooled sample had more than an 80% chance of detecting a treatment effect of 0.5 standard deviations or greater. There was an inverse relation between study quality and estimated treatment effect.

CONCLUSIONS

Tricyclic antidepressants appear to be no more effective than placebo in the treatment of depression in children and adolescents.

Autoantibodies in breast cancer: their use as an aid to early diagnosis

BACKGROUND

There is increasing evidence that the immune system produces a humoral response to cancer-derived antigens. This study assessed the diagnostic potential of autoantibodies to multiple known tumour-associated proteins.

PATIENTS AND METHODS

Sera from normal controls (n = 94), primary breast cancer patients (n = 97) and patients with ductal carcinoma in situ (DCIS) (n = 40) were investigated for the presence of autoantibodies to p53, c-myc, HER2, NY-ESO-1, BRCA1, BRCA2 and MUC1 antigens by enzyme-linked immunosorbent assay.

RESULTS

Reproducibly elevated levels of autoantibodies were seen in at least one of the six antigens in 64% of primary breast cancer patient sera and 45% of patients with DCIS at a specificity of 85%. No significant differences were seen when patients were subdivided by age, tumour size, histological grade, lymph node status or detection methodology.

CONCLUSIONS

Autoantibodies against one or more of these tumour-associated antigens appears to indicate the presence of early-stage breast cancers. Autoantibody assays against a panel of antigens could be used as an aid to mammography in the detection and diagnosis of early primary breast cancer, especially in younger women at increased risk of breast cancer where mammography is known to have reduced sensitivity and specificity.

Elementary school-aged children's reports of their health: a cognitive interviewing study

There are no standard methods for assessing the quality of young children's perceptions of their health and well-being and their ability to comprehend the tasks involved in reporting their health. This research involved three cross-sectional studies using cognitive interviews of 5-11-year-old children (N = 114) to determine their ability to respond to various presentations of pictorially illustrated questions about their health. The samples had a predominance of children in the 5-7-year-old range and families of lower and middle socio-economic status. The research questions in Study 1 involved children's ability to convert their health experiences into scaled responses and relate them to illustrated items (n = 35); Study 2 focused on the type of response format most effectively used by children (n = 19); and Study 3 involved testing children's understanding of health-related terms and use of a specific recall period (n = 60). The results of Study 1 showed that children identified with the cartoon drawing of a child depicted in the illustrated items, typically responding that the child was at or near their own age and of the same gender, with no differences related to race. Study 2 results indicated that children responded effectively to circles of graduated sizes to indicate their response and preferred them to same-size circles or a visual analogue scale. Tests of three-, four-, and five-point response formats demonstrated that children could use them all without confusion. In Study 3, expected age-related differences in understanding were obtained. In fact, the 5-year-old children were unable to understand a sufficient number of items to adequately describe their health. Virtually all children 8 years of age and older were able to fully understand the key terms and presentation of items, used the full five-point range of response options, and accurately used a 4-week recall period. Six- and seven-year-olds were more likely than older children to use only the extreme and middle responses on a five-point scale. No pattern of gender differences in understanding or in use of response options was found. We conclude that children as young as eight are able to report on all aspects of their health experiences and can use a five-point response format. Children aged 6-7 had difficulty with some health-related terms and tended to use extreme responses, but they understood the basic task requirements and were able to report on their health experiences. These results provide the guidance needed to develop and test a pediatric health status questionnaire for children 6-11 years old.

Specification of receptor-binding phenotypes of influenza virus isolates from different hosts using synthetic sialylglycopolymers: non-egg-adapted human H1 and H3 influenza A and influenza B viruses share a common high binding affinity for 6'-sialyl(N-acetyllactosamine)

Synthetic sialylglycoconjugates bearing 3'-sialyllactose, 6'-sialyllactose, or 6'-sialyl(N-acetyllactosamine) moieties attached to the polyacrylic acid carrier (P-3-SL, P-6-SL, and P-6-SLN, respectively) were prepared and tested for their ability to bind to influenza virus isolates from different hosts in a competitive solid phase assay. The virus panel included egg-grown avian and porcine strains, as well as human viruses isolated and propagated solely in mammalian (MDCK) cells and their egg-adapted variants. A clear correlation was observed between the pattern of virus binding of two glycopolymers, P-3-SL and P-6-SLN, and the host species from which the virus was derived. Avian isolates displayed a high binding affinity for P-3-SL and a two to three orders of magnitude lower affinity for P-6-SLN. By contrast, all non-egg-adapted human A and B viruses bound P-6-SLN strongly but did not bind P-3-SL. Unlike the "authentic" human strains, their egg-adapted counterparts acquired an ability to bind P-3-SL, indicative of a shift in the receptor-binding phenotype toward the recognition of Neu5Ac2-3Gal-terminated sugar sequences. Among the porcine viruses and human isolates with porcine hemagglutinin, few displayed an avian-like binding phenotype, while others differed from both avian and human strains by a reduced ability to discriminate between P-3-SL and P-6-SLN. Our data show that sialylglycopolymers may become a useful tool in studies on molecular mechanisms of interspecies transfer, tissue specificity, and other structure-function relationships of the influenza virus hemagglutinin.

5' and 3' terminal nucleotide sequences of the RNA genome segments of influenza virus

EXtensive nucleotide sequence analysis of the 5' and the 3' terminal of the RNA segments of the genome of fowl plague virus, an avian strain of influenza virus, confirms the presence of a common sequence at the 5' terminus of each segment and a common sequence at the 3' terminus of each segment. Between the ends of each individual segment there is a complementary sequence which may be important in the control of transcription and replication of the genome. In addition, the probable sites of initiation of translation of fowl plague virus mRNA are indicated along with the corresponding NH2-terminal amino acid sequences of the virus polypeptides.

Polyadenylation sites for influenza virus mRNA

Polyadenylated transcripts of influenza virus RNA are incomplete copies of the individual genome segments, lacking sequences complementary to the 5'-terminal nucleotides of the virion RNA. By using a procedure which depends on the polyadenylic acid tail of the mRNA being encoded in part by the genome, we have determined that the common tract of uridine residues, approximately 17 to 22 nucleotides from the 5' end of each segment, is the site of polyadenylation of influenza virus mRNA.

Structural changes in the haemagglutinin which accompany egg adaptation of an influenza A(H1N1) virus

Antigenic changes are often induced in the haemagglutinin (HA) of human isolates of influenza A(H1N1) and B viruses during their isolation and propagation in embryonated hens' eggs. In this report we describe molecular changes in the HA of an A(H1N1) virus which accompany egg adaptation. The HA1 amino acid substitutions of egg-adapted variants are located in the vicinity of the receptor binding site. This suggests that egg-adapted variants are selected on the basis of altered receptor site specificity with concomitant effects on the antigenic configuration of the HA molecule. In this study, at least three antigenically distinct groups of egg-adapted variants were observed. These observations have implications for the indiscriminate use of egg-adapted viruses in sero-epidemiological studies and vaccine production.

Does the higher order structure of the influenza virus ribonucleoprotein guide sequence rearrangements in influenza viral RNA?

Subgenomic RNAs (sgRNAs) were isolated from defective interfering virus produced by high multiplicity passage of the human influenza strain A/PR/8/34. Cloning and sequencing of 35 unique sgRNAs revealed that many were about 400 nucleotides long, containing about 200 nucleotides from each of the 5' and 3' ends of a full-length segment. Most of the sgRNAs were derived from segment 1, but there were examples from six other segments, including those encoding the haemagglutinin and neuraminidase. Our analysis of the sequence rearrangements found in sgRNAs indicates that they may be generated from the standard viral segments by a jumping viral polymerase that makes transitions between adjacent regions of the RNA template in the ribonucleoprotein tertiary structure.

Management of frozen shoulder: a systematic review and cost-effectiveness analysis

BACKGROUND

Frozen shoulder is condition in which movement of the shoulder becomes restricted. It can be described as either primary (idiopathic) whereby the aetiology is unknown, or secondary, when it can be attributed to another cause. It is commonly a self-limiting condition, of approximately 1 to 3 years' duration, though incomplete resolution can occur.

OBJECTIVES

To evaluate the clinical effectiveness and cost-effectiveness of treatments for primary frozen shoulder, identify the most appropriate intervention by stage of condition and highlight any gaps in the evidence.

DATA SOURCES

A systematic review was conducted. Nineteen databases and other sources including the Cumulative Index to Nursing and Allied Health (CINAHL), Science Citation Index, BIOSIS Previews and Database of Abstracts of Reviews of Effects (DARE) were searched up to March 2010 and EMBASE and MEDLINE up to January 2011, without language restrictions. MEDLINE, CINAHL and PsycINFO were searched in June 2010 for studies of patients' views about treatment.

REVIEW METHODS

Randomised controlled trials (RCTs) evaluating physical therapies, arthrographic distension, steroid injection, sodium hyaluronate injection, manipulation under anaesthesia, capsular release or watchful waiting, alone or in combination were eligible for inclusion. Patients with primary frozen shoulder (with or without diabetes) were included. Quasi-experimental studies were included in the absence of RCTs and case series for manipulation under anaesthesia (MUA) and capsular release only. Full economic evaluations meeting the intervention and population inclusion criteria of the clinical review were included. Two researchers independently screened studies for relevance based on the inclusion criteria. One reviewer extracted data and assessed study quality; this was checked by a second reviewer. The main outcomes of interest were pain, range of movement, function and disability, quality of life and adverse events. The analysis comprised a narrative synthesis and pair-wise meta-analysis. A mixed-treatment comparison (MTC) was also undertaken. An economic decision model was intended, but was found to be implausible because of a lack of available evidence. Resource use was estimated from clinical advisors and combined with quality-adjusted life-years obtained through mapping to present tentative cost-effectiveness results.

RESULTS

Thirty-one clinical effectiveness studies and one economic evaluation were included. The clinical effectiveness studies evaluated steroid injection, sodium hyaluronate, supervised neglect, physical therapy (mainly physiotherapy), acupuncture, MUA, distension and capsular release. Many of the studies identified were at high risk of bias. Because of variation in the interventions and comparators few studies could be pooled in a meta-analysis. Based on single RCTs, and for some outcomes only, short-wave diathermy may be more effective than home exercise. High-grade mobilisation may be more effective than low-grade mobilisation in a population in which most patients have already had treatment. Data from two RCTs showed that there may be benefit from adding a single intra-articular steroid injection to home exercise in patients with frozen shoulder of < 6 months' duration. The same two trials showed that there may be benefit from adding physiotherapy (including mobilisation) to a single steroid injection. Based on a network of nine studies the MTC found that steroid combined with physiotherapy was the only treatment showing a statistically and clinically significant beneficial treatment effect compared with placebo for short-term pain (standardised mean difference -1.58, 95% credible interval -2.96 to -0.42). This analysis was based on only a subset of the evidence, which may explain why the findings are only partly supportive of the main analysis. No studies of patients' views about the treatments were identified. Average costs ranged from £36.16 for unguided steroid injections to £2204 for capsular release. The findings of the mapping suggest a positive relationship between outcome and European Quality of Life-5 Dimensions (EQ-5D) score: a decreasing visual analogue scale score (less pain) was accompanied by an increasing (better) EQ-5D score. The one published economic evaluation suggested that low-grade mobilisation may be more cost-effective than high-grade mobilisation. Our tentative cost-effectiveness analysis suggested that steroid alone may be more cost-effective than steroid plus physiotherapy or physiotherapy alone. These results are very uncertain.

LIMITATIONS

The key limitation was the lack of data available. It was not possible to undertake the planned synthesis exploring the influence of stage of frozen shoulder or the presence of diabetes on treatment effect. As a result of study diversity and poor reporting of outcome data there were few instances where the planned quantitative synthesis was possible or appropriate. Most of the included studies had a small number of participants and may have been underpowered. The lack of available data made the development of a decision-analytic model implausible. We found little evidence on treatment related to stage of condition, treatment pathways, the impact on quality of life, associated resource use and no information on utilities. Without making a number of questionable assumptions modelling was not possible.

CONCLUSIONS

There was limited clinical evidence on the effectiveness of treatments for primary frozen shoulder. The economic evidence was so limited that no conclusions can be made about the cost-effectiveness of the different treatments. High-quality primary research is required.

Social class gradients in health during adolescence

STUDY OBJECTIVE

To review existing data on social class gradients in adolescent health and to examine whether such gradients exist in new data concerning US adolescents.

DESIGN

Review of relevant publications and unpublished data; regression analyses using adolescent self reported health status data to determine whether there are gradients by social class, using three classes categorised by adolescent reported parental work status and education.

PARTICIPANTS

Adolescents of ages 11-17.

MAIN RESULTS

Findings from the literature indicate the presence of social class gradients in some but not all aspects of adolescent health. Results from new data showed social class gradients in several domains of health and in profiles of health. The likelihood of being satisfied with one's health, of being more resilient (better family involvement, better problem solving, more physical activity, better home safety), having higher school achievement, and of being in the best health profiles were significantly and progressively greater as social class rose. Moreover, the probability of being in the poorest health profile type group was progressively higher as social class declined.

CONCLUSIONS

The review of existing data and the new findings support the existence of social class gradients in satisfaction with one's health, in resilience to health threats, in school achievement, and in being in the best health overall (as manifested by the health profiles composed of four major domains of health). The study had two especially notable findings: (1) the paucity of studies using the same or similar indicators, and (2) the consistent existence of social class gradients in characteristics related to subsequent health, particularly intake of nutritional foods and physical activity. The sparseness of existing data and the different aspects of health investigated in the relatively few studies underscore the need for (1) the development of conceptual models specifically focused on adolescent health and social class; (2) additional inquiry into the measurement of social class and adolescent perceptions of class; (3) inclusion of contextual variables in study design; and (4) longitudinal cohort studies to better understand the specific determinants of health during adolescence.

Alterations in the hemagglutinin associated with adaptation of influenza B virus to growth in eggs

In 1943 Burnet reported on changes in the hemagglutinating properties of human influenza virus which occurred during adaptation of the virus to growth in chicken eggs. Only recently has direct evidence been presented that these changes affect the antigenic properties of the virus. Schild et al. (G. C. Schild, J. S. Oxford, J. C. deJong, and R. G. Webster (1983), Nature (London) 303, 706-709) demonstrated that egg adaptation of influenza B virus selects variants which are antigenically distinct from virus grown from the same source in mammalian cells. The molecular changes in the hemagglutinin (HA) of influenza B virus associated with adaptation to growth in eggs have now been identified. A specific glycosylation site at the distal tip of the HA of influenza B virus grown exclusively in mammalian cell culture is lost or altered during egg adaptation. Since the HA functions in adsorption of virus to cells, it is concluded that removal or modification of an oligosaccharide structure at this position is required for influenza B virus to attach to and infect the allantois cells of the egg and that this has important implications for the antigenic configuration of the molecule.