Measurement of deeply virtual compton scattering beam-spin asymmetries

The beam-spin asymmetries in the hard exclusive electroproduction of photons on the proton (e p-->epgamma) were measured over a wide kinematic range and with high statistical accuracy. These asymmetries result from the interference of the Bethe-Heitler process and of deeply virtual Compton scattering. Over the whole kinematic range (x(B) from 0.11 to 0.58, Q2 from 1 to 4.8 GeV2, -t from 0.09 to 1.8 GeV2), the azimuthal dependence of the asymmetries is compatible with expectations from leading-twist dominance, A approximately a sinphi/(1+c cosphi). This extensive set of data can thus be used to constrain significantly the generalized parton distributions of the nucleon in the valence quark sector.

An under-recognized complication of treatment of acute severe asthma

A 39-year-old man presented to the emergency department (ED) in severe respiratory distress. He had a prior diagnosis of brittle asthma and had been admitted on several occasions but never previously ventilated. Therapy given in the first 3 hours of arrival included nebulized salbutamol (5 mg, x5), ipratropium bromide (0.5 mg), intravenous hydrocortisone (200 mg), and magnesium sulfate (2 g). His arterial blood gases continued to deteriorate. He was then given an intravenous bolus of salbutamol (250 microg) and heliox via facemask. His worsening status necessitated invasive ventilation. His hypercapnia and resultant respiratory acidosis improved rapidly, but there was a concurrent accumulation of lactic acid resulting in acidemia. This patient had lactic acidosis as a direct effect of administration of salbutamol. The development of hazardous salbutamol-induced toxicity in acute severe asthma is discussed.

Variation in HIV-1 R5 macrophage-tropism correlates with sensitivity to reagents that block envelope: CD4 interactions but not with sensitivity to other entry inhibitors

Background

HIV-1 R5 viruses cause most of the AIDS cases worldwide and are preferentially transmitted compared to CXCR4-using viruses. Furthermore, R5 viruses vary extensively in capacity to infect macrophages and highly macrophage-tropic variants are frequently identified in the brains of patients with dementia. Here, we investigated the sensitivity of R5 envelopes to a range of inhibitors and antibodies that block HIV entry. We studied a large panel of R5 envelopes, derived by PCR amplification without culture from brain, lymph node, blood and semen. These R5 envelopes conferred a wide range of macrophage tropism and included highly macrophage-tropic variants from brain and non-macrophage-tropic variants from lymph node.

Results

R5 macrophage-tropism correlated with sensitivity to inhibition by reagents that inhibited gp120:CD4 interactions. Thus, increasing macrophage-tropism was associated with increased sensitivity to soluble CD4 and to IgG-CD4 (PRO 542), but with increased resistance to the anti-CD4 monoclonal antibody (mab), Q4120. These observations were highly significant and are consistent with an increased affinity of envelope for CD4 for macrophage-tropic envelopes. No overall correlations were noted between R5 macrophage-tropism and sensitivity to CCR5 antagonists or to gp41 specific reagents. Intriguingly, there was a relationship between increasing macrophage-tropism and increased sensitivity to the CD4 binding site mab, b12, but decreased sensitivity to 2G12, a mab that binds a glycan complex on gp120.

Conclusion

Variation in R5 macrophage-tropism is caused by envelope variation that predominantly influences sensitivity to reagents that block gp120:CD4 interactions. Such variation has important implications for therapy using viral entry inhibitors and for the design of envelope antigens for vaccines.

Is telomere length in peripheral blood lymphocytes correlated with cancer susceptibility or radiosensitivity?

Mean terminal restriction fragment (TRF) lengths in white blood cells (WBCs) have been previously found to be associated with breast cancer. To assess whether this marker could be used as a test for breast cancer susceptibility in women, TRF length was measured in 72 treated female breast cancer patients and 1696 unaffected female controls between the ages of 45 and 77 from the Twin Research Unit at St Thomas' Hospital, as well as 140 newly diagnosed breast cancer cases and 108 mammographically screened unaffected controls from Guy's Hospital. Mean TRF was also tested for correlation with chromosome radiosensitivity and apoptotic response in the Guy's Hospital patients. After adjusting for age, smoking and body mass index, there was no significant difference in TRF lengths between the treated breast cancer patients and unaffected controls (P=0.71). A positive correlation between age-adjusted apoptotic response and mean TRF in newly diagnosed untreated breast cancer patients (P=0.008) was identified but no significant difference in TRF lengths between breast cancer patients and unaffected controls was detected (P=0.53). This suggests that TRF lengths in WBC, is not a marker of breast cancer susceptibility and does not vary significantly between affected women before and after treatment.

Towards automated segmentation and classification of masses in mammograms

This paper presents a straightforward approach to detecting and segmenting mammographic mass cores. The method utilizes adaptive thresholding applied to a contrast-enhanced version of the gray-scale mammogram, where the threshold is a function of the localized gray-level mean and variance. To assess the method's efficacy, it is applied to a database of 62 mammograms, each containing a suspicious mass (39 benign and 23 malignant). Each test case consists of a gray-scale image and a binary image containing a radiologist segmentation of the mass. After segmentation, a variety of features are extracted, including several based on the normalized radial length, rubber band straightening algorithm, gray-level statistics, and patient age. Next, step-wise linear discriminant analysis is utilized for feature reduction and optimization. The same procedure is applied to the manually segmented masses. Analysis of the optimized features resulted in an ROC curve area of Az = 0.8796 and Az = 0.8719 for the automated and manually segmented masses, respectively.

Estrogen-induced alterations in amh and dmrt1 expression signal for disruption in male sexual development in the zebrafish

Dmrt1 and amh are genes involved in vertebrate sex differentiation. In this study, we cloned dmrt1 and amh cDNAs in zebrafish (Danio rerio) and investigated the effects of exposure to 17a-ethinylestradiol (EE2), during early life on their patterns of expression and impact on the subsequent gonadal phenotype. Expression of both amh and dmrt1 in embryos was detected as early as at 1 day post fertilization (dpf) and enhanced expression of amh from 25 dpf was associated with the period of early gonadal differentiation. Sex-dependent differences in enhanced green fluorescent protein transgene expression driven by the promoter of the germ cell-specific vas gene were exploited to show that at 28dpf and 56dpf both amh and dmrt1 mRNA were overexpressed in males compared with females. Exposure during early life to environmentally relevant concentrations of EE2 had a suppressive effect on the expression of both amh and dmrt1 mRNAs and this was associated with a cessation/retardation in male gonadal sex development. Our findings indicate that estrogen-induced suppression in expression of dmrt1 and amh during early life correlate with subsequent disruptive effects on the sexual phenotype in males.

Osteopenia (OP) induced by 6 and 18 months androgen deprivation (AD)

5123

Background: In a trial evaluating the optimal duration of AD in locally advanced prostate cancer (PC) we sought to determine whether 18 months of zoledronate (Zd) would reverse AD induced OP and reduce bony failure. Methods: In the four arm 2x2 TROG 03.04 (RADAR) trial, men with T2b,c-4 and T2a (Gleason score >6, PSA >10) N0 M0 PC (but without osteoporosis) were randomised to leuprotide (Lp) 22.5 mgs i.m. 3 monthly for 6 months starting 5 months prior to radiotherapy (RT) in Arm A, or the same treatment with Zd mgs i.v.i. 3 months for 18 months commencing on Day 1 (in Arms B and D), or with Lp 22.5 mg i.m. 3 monthly for 12 months after RT (in Arms C and D). Hip and spinal bone mineral densities (BMD) were measured before treatment (bt) and then at 2 and 4 years using DEXA and differences between trial arms were assessed by paired t tests. OP was defined by T- scores <-1. Results: Between October 2003 and January 2006, 930 men were randomized. 124 men with BMD measures bt and at 2 years are evaluable. Mean change (±SD) in BMD between 0 and 2 years was -0.005 ±0.05 (p=0.57) in Arm A, 0.085 ±0.06 (p=<0.001) in Arm B, 0.054 ±0.07 (p=<0.001) in Arm C, and 0.065 ±0.05 (p=<0.001) in Arm D. 98 men had normal BMD bt. Of these 6 of 51 in Arms A, C (no Zd) have developed OP at 2 years while none of 47 in Arms B, D (+Zd) have as yet. Conclusions: At 2 years OP caused by 6 months AD is minimal, but remains significant after 18 months AD. This is reversed by 18 months Zd, but further follow up will determine whether this degree of OP resolves with time or causes fractures.

No significant financial relationships to disclose.

Recently published papers: the Jekyll and Hyde of oxygen, neuromuscular blockade and good vibrations?

This issue's recently published papers commentary takes a long hard look at the surprisingly topically issue of oxygen. To give a balanced perspective, topical ventilatory studies are also discussed.

Comparative cohort study of the outcomes of deep lamellar keratoplasty and penetrating keratoplasty for keratoconus

AIM

To compare the outcomes and complications of deep lamellar keratoplasty (DLK) and penetrating keratoplasty (PK) for keratoconus.

METHODS

A cohort of 20 consecutive PKs, for keratoconus, was compared with 20 consecutive DLKs, for keratoconus. The PKs were performed between June 2000 and July 2001, the DLKs between October 2001 and October 2002. Surgery was performed by one surgeon. Best-corrected visual acuities (BCVA), refraction and complications were recorded at the time of surgery, 6 and 12 months postoperatively. chi(2)-tests were used to compare visual acuity outcomes and independent t-tests in the analysis of astigmatism.

RESULTS

Groups were comparable for age, sex, and ethnicity. All PKs were uncomplicated. Two of the DLK group had microperforations of Descemet's membrane. There was no significant difference in the proportion of patients achieving 6/9 or better between the PK and DLK groups (85 vs 78%, P=0.54). PK patients were, however, more likely than the DLKs to achieve 6/6 at 1 year; 70% (14/20) of PKs compared to 22% of (4/18) DLKs (P=0.04). Astigmatism was significantly higher in the PKs compared to the DLKs (P=0.022). There were two cases of graft rejection in the PK group, while none in the DLKs.

CONCLUSIONS

This study confirms good visual results from both PK and DLK in keratoconus with similarly high percentages reaching 6/9 BCVA. DLK appears to cause less astigmatism and also has the advantage of no endothelial graft rejection. The apparent cost, however, is a reduction in the likelihood of achieving 6/6 BCVA.

Non-macrophage-tropic human immunodeficiency virus type 1 R5 envelopes predominate in blood, lymph nodes, and semen: implications for transmission and pathogenesis

Human immunodeficiency virus type 1 (HIV-1) R5 isolates that predominantly use CCR5 as a coreceptor are frequently described as macrophage tropic. Here, we compare macrophage tropism conferred by HIV-1 R5 envelopes that were derived directly by PCR from patient tissue. This approach avoids potentially selective culture protocols used in virus isolation. Envelopes were amplified (i) from blood and semen of adult patients and (ii) from plasma of pediatric patients. The phenotypes of these envelopes were compared to those conferred by an extended panel of envelopes derived from brain and lymph node that we reported previously. Our results show that R5 envelopes vary by up to 1,000-fold in their capacity to confer infection of primary macrophages. Highly macrophage-tropic envelopes were predominate in brain but were infrequent in semen, blood, and lymph node samples. We also confirmed that the presence of N283 in the C2 CD4 binding site of gp120 is associated with HIV-1 envelopes from the brain but absent from macrophage-tropic envelopes amplified from blood and semen. Finally, we compared infection of macrophages, CD4(+) T cells, and peripheral blood mononuclear cells (PBMCs) conferred by macrophage-tropic and non-macrophage-tropic envelopes in the context of full-length replication competent viral clones. Non-macrophage-tropic envelopes conferred low-level infection of macrophages yet infected CD4(+) T cells and PBMCs as efficiently as highly macrophage-tropic brain envelopes. The lack of macrophage tropism for the majority of the envelopes amplified from lymph node, blood, and semen is striking and contrasts with the current consensus that R5 primary isolates are generally macrophage tropic. The extensive variation in R5 tropism reported here is likely to have an important impact on pathogenesis and on the capacity of HIV-1 to transmit.

Recently published papers: what not to do and how not to do it?

Controversies abound in the areas of blood transfusion, albumin, lipoproteins in sepsis and pulmonary artery catheters. We are also making too many errors, but at least there is a new nitric oxide therapy in the offing.

First measurement of the transverse spin asymmetries of the deuteron in semi-inclusive deep inelastic scattering

First measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarized 6LiD target are presented. The data were taken in 2002 with the COMPASS spectrometer using the muon beam of the CERN SPS at 160 GeV/c. The Collins asymmetry turns out to be compatible with zero, as does the measured Sivers asymmetry within the present statistical errors.

Statistics review 14: Logistic regression

This review introduces logistic regression, which is a method for modelling the dependence of a binary response variable on one or more explanatory variables. Continuous and categorical explanatory variables are considered.

Statistics review 13: receiver operating characteristic curves

This review introduces some commonly used methods for assessing the performance of a diagnostic test. The sensitivity, specificity and likelihood ratio of a test are discussed. The uses of the receiver operating characteristic curve and the area under the curve are explained.

Statistics review 12: survival analysis

This review introduces methods of analyzing data arising from studies where the response variable is the length of time taken to reach a certain end-point, often death. The Kaplan–Meier methods, log rank test and Cox's proportional hazards model are described.

Statistics review 11: assessing risk

Relative risk and odds ratio have been introduced in earlier reviews (see Statistics reviews 3, 6 and 8). This review describes the calculation and interpretation of their confidence intervals. The different circumstances in which the use of either the relative risk or odds ratio is appropriate and their relative merits are discussed. A method of measuring the impact of exposure to a risk factor is introduced. Measures of the success of a treatment using data from clinical trials are also considered.

Do Toxoplasma gondii RH strain tachyzoites evolve during continuous passage?

AIM

To examine three lineages of Toxoplasma gondii RH strain in terms of performance in the dye test, culture, and gene expression.

METHODS

Historical data (culture growth and performance in the dye test) from three lineages of RH strain tachyzoites (B, J, and Q) that had been continuously cultured in HeLa cells was assessed. Tachyzoite harvests obtained during continuous cell culture were retrieved from liquid nitrogen and cultured in HeLa cells, providing mRNA that was extracted and used to study gene expression using random amplified polymorphic DNA analysis at different stages of lineage adaptation to continuous culture.

RESULTS

The B and Q lineages consistently produced tachyzoites that were successfully used in the dye test and their gene expression was stable after multiple passages. The J lineage had unpredictable growth, tachyzoites unsuitable for use in the dye test, and changing gene expression with multiple passage.

CONCLUSION

This study has explained some anomalies in the performance of different stocks of T gondii, and suggests that lineages that are still evolving in cell culture should be avoided.

Statistics review 9: one-way analysis of variance

This review introduces one-way analysis of variance, which is a method of testing differences between more than two groups or treatments. Multiple comparison procedures and orthogonal contrasts are described as methods for identifying specific differences between pairs of treatments.

Statistics review 8: Qualitative data - tests of association

This review introduces methods for investigating relationships between two qualitative (categorical) variables. The χ² test of association is described, together with the modifications needed for small samples. The test for trend, in which at least one of the variables is ordinal, is also outlined. Risk measurement is discussed. The calculation of confidence intervals for proportions and differences between proportions are described. Situations in which samples are matched are considered.

Statistics review 7: Correlation and regression

The present review introduces methods of analyzing the relationship between two quantitative variables. The calculation and interpretation of the sample product moment correlation coefficient and the linear regression equation are discussed and illustrated. Common misuses of the techniques are considered. Tests and confidence intervals for the population parameters are described, and failures of the underlying assumptions are highlighted.

A critique of age estimation using attrition as the sole indicator

The age determination of skeletal remains has been carried out using anthropological examination of the remaining bones and dentition. The aging of the dentition is based on attrition which, if physiological will correlate with age. Occasionally the only material available is a single tooth or a few teeth, or in the case of a living person, teeth in situ. In certain cases microscopic examination of the teeth may not be possible and the age estimation is then often determined by the degree of attrition associated with the tooth. In more recent times the causes of attrition have involved other factors such as bruxism, diet, environment and medication. The weaknesses and limitations of age estimation by examination of dental attrition as the sole indicator of age are highlighted.

The current status of lip prints and their use for identification

The use of lip prints for human identification was first suggested in 1950 and research was carried out on lip prints in the 1960s and early 1970s, resuming in the last few years. Although lip print identification has been utilized in court in isolated cases more research needs to be conducted in this field with regard to confirmation of uniqueness, and the collection and interpretation of evidence. Lip print identification needs to be acceptable in court as scientifically evidence based.

Eta photoproduction on the proton for photon energies from 0.75 to 1.95 GeV

Differential cross sections for gammap-->etap have been measured with tagged real photons for incident photon energies from 0.75 to 1.95 GeV. Mesons were identified by missing mass reconstruction using kinematical information for protons scattered in the production process. The data provide the first extensive angular distribution measurements for the process above W=1.75 GeV. Comparison with preliminary results from a constituent quark model support the suggestion that a third S11 resonance with mass approximately 1.8 GeV couples to the etaN channel.

How useful is the bispectral index in the management of ICU patients?

If you want to objectively quantify the level of sedation the intuitive solution must be to monitor the brain directly. However, due to the complexity of this organ, and our limited understanding of consciousness, this remains a daunting challenge. For many years, researchers have investigated the electrical activity of the brain and its relationship with conscious level. Over the last few years, a derived variable from the EEG, the Bispectral Index (BIS), has been developed, which appears to correlate quite well with the level of pharmacological sedation.

Are teamwork and professional autonomy compatible, and do they result in improved hospital care?

A postal questionnaire survey of 10 022 staff nurses in 32 hospitals in England was undertaken to explore the relationship between interdisciplinary teamwork and nurse autonomy on patient and nurse outcomes and nurse assessed quality of care. The key variables of nursing autonomy, control over resources, relationship with doctors, emotional exhaustion, and decision making were found to correlate with one another as well as having a relationship with nurse assessed quality of care and nurse satisfaction. Nursing autonomy was positively correlated with better perceptions of the quality of care delivered and higher levels of job satisfaction. Analysis of team working by job characteristics showed a small but significant difference in the level of teamwork between full time and part time nurses. No significant differences were found by type of contract (permanent v short term), speciality of ward/unit, shift length, or job title. Nurses with higher teamwork scores were significantly more likely to be satisfied with their jobs, planned to stay in them, and had lower burnout scores. Higher teamwork scores were associated with higher levels of nurse assessed quality of care, perceived quality improvement over the last year, and confidence that patients could manage their care when discharged. Nurses with higher teamwork scores also exhibited higher levels of autonomy and were more involved in decision making. A strong association was found between teamwork and autonomy; this interaction suggests synergy rather than conflict. Organisations should therefore be encouraged to promote nurse autonomy without fearing that it might undermine teamwork.

Statistics review 5: Comparison of means

The present review introduces the commonly used t-test, used to compare a single mean with a hypothesized value, two means arising from paired data, or two means arising from unpaired data. The assumptions underlying these tests are also discussed.

What are the challenges of translating positive trial results in severe sepsis into clinical practice? A media roundtable debate, 18 March 2002, Brussels, Belgium

The clinical syndrome of sepsis is common, increasing in incidence and responsible for as many deaths annually as ischaemic heart disease. Two recent interventional trials have demonstrated that early recognition and intervention can result in dramatic reductions in acute (28-day) mortality. This roundtable discussion was convened to identify ways in which these recent advances could be translated into clinical practice. The first obstacle surrounds the woolly and confusing terminology surrounding 'sepsis' with the systemic inflammatory response syndrome (SIRS) model largely discredited. Overcoming this should facilitate wider recognition, not only among health care providers (in particular those working in acute specialties outside intensive care units [ICUs]) but also politicians and the general public. Such education is vital if early recognition and intervention are to be successfully implemented.

Statistics review 1: presenting and summarising data

The present review is the first in an ongoing guide to medical statistics, using specific examples from intensive care. The first step in any analysis is to describe and summarize the data. As well as becoming familiar with the data, this is also an opportunity to look for unusually high or low values (outliers), to check the assumptions required for statistical tests, and to decide the best way to categorize the data if this is necessary. In addition to tables and graphs, summary values are a convenient way to summarize large amounts of information. This review introduces some of these measures. It describes and gives examples of qualitative data (unordered and ordered) and quantitative data (discrete and continuous); how these types of data can be represented figuratively; the two important features of a quantitative dataset (location and variability); the measures of location (mean, median and mode); the measures of variability (range, interquartile range, standard deviation and variance); common distributions of clinical data; and simple transformations of positively skewed data.

Statistics review 4: sample size calculations

The present review introduces the notion of statistical power and the hazard of under-powered studies. The problem of how to calculate an ideal sample size is also discussed within the context of factors that affect power, and specific methods for the calculation of sample size are presented for two common scenarios, along with extensions to the simplest case.

Statistics review 2: samples and populations

The previous review in this series introduced the notion of data description and outlined some of the more common summary measures used to describe a dataset. However, a dataset is typically only of interest for the information it provides regarding the population from which it was drawn. The present review focuses on estimation of population values from a sample.

Statistics review 6: Nonparametric methods

The present review introduces nonparametric methods. Three of the more common nonparametric methods are described in detail, and the advantages and disadvantages of nonparametric versus parametric methods in general are discussed.

Statistics review 3: hypothesis testing and P values

The present review introduces the general philosophy behind hypothesis (significance) testing and calculation of P values. Guidelines for the interpretation of P values are also provided in the context of a published example, along with some of the common pitfalls. Examples of specific statistical tests will be covered in future reviews.

An audit of screening for familial breast cancer before 50 years in the South Thames Region – have we got it right?

We have carried out an audit of breast screening by mammography under 50 years of age in a cohort of 192 women attending family cancer clinics run by the South Thames genetic services. Of these women, six came from families in which a BRCA mutation had been identified, 61 had > 50%, 35 a 20-50% and 90 had < 20% chance of carrying a high risk mutation. In the 192 women in the screened cohort, 9 breast cancers were diagnosed (4.7%), all in high-risk women. Three were diagnosed at the prevalence screen. Three were detected mammographically at subsequent screening rounds; three were detected by breast self-examination (BSE) between screening episodes. One interval cancer was visible on mammogram at presentation but not at screening five months previously. A second cancer was also visible on mammogram at presentation but the normal screening mammogram had been 17 months earlier, outside the recommended interval. The remaining interval cancer was not visible on the mammogram. A total of 363 two-view screening mammograms were performed in the 280 person-years of follow-up; 109 additional investigations were generated: 23 recall mammograms, 18 symptomatic mammograms, 45 ultrasounds, 12 aspiration cytologies and 11 biopsies. Cytology diagnosed malignancy in 1 of 12 cases; breast biopsy in 9 of 11 cases. Twenty-three additional women had ultrasound screening only. This audit suggests that screening below the age 50 years may be unnecessary in families with a low chance of having a BRCA1 or -2 mutation, but it is important to screen high-risk women at least annually and possibly under 35 years.