Matching One Sample According to Two Criteria in Observational Studies

Multivariate matching has two goals: (i) to construct treated and control groups that have similar distributions of observed covariates, and (ii) to produce matched pairs or sets that are homogeneous in a few key covariates. When there are only a few binary covariates, both goals may be achieved by matching exactly for these few covariates. Commonly, however, there are many covariates, so goals (i) and (ii) come apart, and must be achieved by different means. As is also true in a randomized experiment, similar distributions can be achieved for a high-dimensional covariate, but close pairs can be achieved for only a few covariates. We introduce a new polynomial-time method for achieving both goals that substantially generalizes several existing methods; in particular, it can minimize the earthmover distance between two marginal distributions. The method involves minimum cost flow optimization in a network built around a tripartite graph, unlike the usual network built around a bipartite graph. In the tripartite graph, treated subjects appear twice, on the far left and the far right, with controls sandwiched between them, and efforts to balance covariates are represented on the right, while efforts to find close individual pairs are represented on the left. In this way, the two efforts may be pursued simultaneously without conflict. The method is applied to our on-going study in the Medicare population of the relationship between superior nursing and sepsis mortality. The match2C package in R implements the method.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

The widespread use of topical antimicrobials enriches for resistance in Staphylococcus aureus isolated from patients with atopic dermatitis

BACKGROUND

Carriage rates of Staphylococcus aureus on affected skin in atopic dermatitis (AD) are approximately 70%. Increasing disease severity during flares and overall disease severity correlate with increased burden of S. aureus. Treatment in AD therefore often targets S. aureus with topical and systemic antimicrobials.

OBJECTIVES

To determine whether antimicrobial sensitivities and genetic determinants of resistance differed in S. aureus isolates from the skin of children with AD and healthy child nasal carriers.

METHODS

In this case-control study, we compared S. aureus isolates from children with AD (n = 50) attending a hospital dermatology department against nasal carriage isolates from children without skin disease (n = 49) attending a hospital emergency department for noninfective conditions. Using whole genome sequencing we generated a phylogenetic framework for the isolates based on variation in the core genome, then compared antimicrobial resistance phenotypes and genotypes between disease groups.

RESULTS

Staphylococcus aureus from cases and controls had on average similar numbers of phenotypic resistances per isolate. Case isolates differed in their resistance patterns, with fusidic acid resistance (Fus^R ) being significantly more frequent in AD (P = 0·009). The genetic basis of Fus^R also differentiated the populations, with chromosomal mutations in fusA predominating in AD (P = 0·049). Analysis revealed that Fus^R evolved multiple times and via multiple mechanism in the population. Carriage of plasmid-derived qac genes, which have been associated with reduced susceptibility to antiseptics, was eight times more frequent in AD (P = 0·016).

CONCLUSIONS

The results suggest that strong selective pressure drives the emergence and maintenance of specific resistances in AD.

Accurate Differentiation of Carotenoid Pigments Using Flight Representative Raman Spectrometers

Raman spectrometers will be utilized on two Mars rover missions, ExoMars and Mars 2020, in the near future, to search for evidence of life and habitable geological niches on Mars. Carotenoid pigments are recognized target biomarkers, and as they are highly active in Raman spectroscopy, they can be readily used to characterize the capabilities of space representative instrumentation. As part of the preparatory work being performed for the ExoMars mission, a gypsum crust colonized by microorganisms was interrogated with commercial portable Raman instruments and a flight representative Raman laser spectrometer. Four separate layers, each exhibiting different coloration resulting from specific halophilic microorganism activities within the gypsum crust, were studied by using two excitation wavelengths: 532 and 785 nm. Raman or fluorescence data were readily obtained during the present study. Gypsum, the main constituent of the crust, was detected with both excitation wavelengths, while the resonance Raman signal associated with carotenoid pigments was only detected with a 532 nm excitation wavelength. The fluorescence originating from bacteriochlorophyll a was found to overwhelm the Raman signal for the layer colonized by sulfur bacteria when interrogated with a 785 nm excitation wavelength. Finally, it was demonstrated that portable instruments and the prototype were capable of detecting a statistically significant difference in band positions of carotenoid signals between the sample layers. Key Words: Gypsum-Raman spectrometers-Carotenoids-ExoMars-Mars exploration-Band position shift. Astrobiology 17, 351-362.

The reporting of study and population characteristics in degenerative cervical myelopathy: A systematic review

OBJECT

Degenerative cervical myelopathy [DCM] is a disabling and increasingly prevalent condition. Variable reporting in interventional trials of study design and sample characteristics limits the interpretation of pooled outcomes. This is pertinent in DCM where baseline characteristics are known to influence outcome. The present study aims to assess the reporting of the study design and baseline characteristics in DCM as the premise for the development of a standardised reporting set.

METHODS

A systematic review of MEDLINE and EMBASE databases, registered with PROSPERO (CRD42015025497) was conducted in accordance with PRISMA guidelines. Full text articles in English, with >50 patients (prospective) or >200 patients (retrospective), reporting outcomes of DCM were deemed to be eligible.

RESULTS

A total of 108 studies involving 23,876 patients, conducted world-wide, were identified. 33 (31%) specified a clear primary objective. Study populations often included radiculopathy (51, 47%) but excluded patients who had undergone previous surgery (42, 39%). Diagnositic criteria for myelopathy were often uncertain; MRI assessment was specified in only 67 (62%) of studies. Patient comorbidities were referenced by 37 (34%) studies. Symptom duration was reported by 46 (43%) studies. Multivariate analysis was used to control for baseline characteristics in 33 (31%) of studies.

CONCLUSIONS

The reporting of study design and sample characteristics is variable. The development of a consensus minimum dataset for (CODE-DCM) will facilitate future research synthesis in the future.

Production of Highly Polarized Positrons Using Polarized Electrons at MeV Energies

The Polarized Electrons for Polarized Positrons experiment at the injector of the Continuous Electron Beam Accelerator Facility has demonstrated for the first time the efficient transfer of polarization from electrons to positrons produced by the polarized bremsstrahlung radiation induced by a polarized electron beam in a high-Z target. Positron polarization up to 82% have been measured for an initial electron beam momentum of 8.19  MeV/c, limited only by the electron beam polarization. This technique extends polarized positron capabilities from GeV to MeV electron beams, and opens access to polarized positron beam physics to a wide community.

Detection of pigments of halophilic endoliths from gypsum: Raman portable instrument and European Space Agency's prototype analysis

A prototype instrument, under development at the University of Leicester, for the future European Space Agency (ESA) ExoMars mission, was used for the analysis of microbial pigments within a stratified gypsum crust from a hypersaline saltern evaporation pond at Eilat (Israel). Additionally, the same samples were analysed using a miniaturized Raman spectrometer, featuring the same 532 nm excitation. The differences in the position of the specific bands, attributed to carotenoid pigments from different coloured layers, were minor when analysed by the ESA prototype instrument; therefore, making it difficult to distinguish among the different pigments. The portable Delta Nu Advantage instrument allowed for the discrimination of microbial carotenoids from the orange/green and purple layers. The purpose of this study was to complement previous laboratory results with new data and experience with portable or handheld Raman systems, even with a dedicated prototype Raman system for the exploration of Mars. The latter is equipped with an excitation wavelength falling within the carotenoid polyene resonance region. The ESA prototype Raman instrument detected the carotenoid pigments (biomarkers) with ease, although further detailed distinctions among them were not achieved.

Raman spectroscopy on Mars: identification of geological and bio-geological signatures in Martian analogues using miniaturized Raman spectrometers

The first Raman spectrometers to be used for in situ analysis of planetary material will be launched as part of powerful, rover-based analytical laboratories within the next 6 years. There are a number of significant challenges associated with building spectrometers for space applications, including limited volume, power and mass budgets, the need to operate in harsh environments and the need to operate independently and intelligently for long periods of time (due to communication limitations). Here, we give an overview of the technical capabilities of the Raman instruments planned for future planetary missions and give a review of the preparatory work being pursued to ensure that such instruments are operated successfully and optimally. This includes analysis of extremophile samples containing pigments associated with biological processes, synthetic materials which incorporate biological material within a mineral matrix, planetary analogues containing low levels of reduced carbon and samples coated with desert varnish that incorporate both geo-markers and biomarkers. We discuss the scientific importance of each sample type and the challenges using portable/flight-prototype instrumentation. We also report on technical development work undertaken to enable the next generation of Raman instruments to reach higher levels of sensitivity and operational efficiency.

Occurrence of microplastics in the gastrointestinal tract of pelagic and demersal fish from the English Channel

Microplastics are present in marine habitats worldwide and laboratory studies show this material can be ingested, yet data on abundance in natural populations is limited. This study documents microplastics in 10 species of fish from the English Channel. 504 Fish were examined and plastics found in the gastrointestinal tracts of 36.5%. All five pelagic species and all five demersal species had ingested plastic. Of the 184 fish that had ingested plastic the average number of pieces per fish was 1.90±0.10. A total of 351 pieces of plastic were identified using FT-IR Spectroscopy; polyamide (35.6%) and the semi-synthetic cellulosic material, rayon (57.8%) were most common. There was no significant difference between the abundance of plastic ingested by pelagic and demersal fish. Hence, microplastic ingestion appears to be common, in relatively small quantities, across a range of fish species irrespective of feeding habitat. Further work is needed to establish the potential consequences.

A Randomised Study Comparing the Effects of Adjuvant Anastrozole (A), Letrozole (L) and Exemestane (E) on Lipid Metabolism

Background:Aromatase inhibitors (AIs) reduce circulating oestrogen which may have a detrimental effect on lipid metabolism and subsequently ↑ cardiovascular risk. This study compares the effects of adjuvant A, L and E on lipid metabolism.Patients and Methods:This was an open, randomised pharmacodynamic study. Plasma lipids were measured in 120 postmenopausal women with invasive ER +ve breast cancer. As part of their adjuvant hormone therapy, patients were randomized to receive either:• 4 months of A or• 4 months of L or• 4 months of EFasting blood and urine samples were collected at the same time of day on each of (a) the day of entry, (b) after 3 months and (c) after 4 months. Patients were then switched to tamoxifen (T) and further samples collected after 12 months.• Triglycerides, cholesterol, ApoB and cLDL were measured.↑ levels are associated with ↑ cardiovascular risk.• ApoA-1 and HDL were also measured.↑ levels are associated with ↓ cardiovascular risk.Analyses were performed using repeated measures or analysis of covariance.ResultsDifferences between A vs L vs ETriglycerides E significantly ↓ triglycerides. There was a borderline significant difference between the drugs (p=0.055).Cholesterol E significantly ↓ cholesterol (p=0.03).ApoB No significant changes were detected.cLDL No significant changes were detected.ApoA-1 There were no significant differences detected between A or L although the fall with E was less but not significantly different to A or L (p=0.08).HDL E significantly ↓ HDL (p=0.008).Differences between steroidal vs non-steroidal AIsTriglyceride and ApoA-1 levels fell significantly more with E compared to the non-steroidal A+L (p=0.02, p=0.045 respectively).Effects of tamoxifenChanges from baseline after treatment on AIs and subsequent treatment with TFollowing T there was no evidence to suggest that the changes from baseline were influenced by the type of AI that patients received.Changes from end of treatment on AIs and subsequent treatment with TT increased HDL by a statistically significant greater amount following E than it did after A or L (p=0.009). From the end of treatment with AIs, T produced significant rises in triglyceride (p=0.0001), HDL (p=0.006) and ApoA1 (p=0.0003), and significant falls in cholesterol (p=0.03) and cLDL (p<0.0001).Conclusions:There were no significant differences between letrozole, anastrozole and exemestane and their effects on cholesterol, HDL, cLDL or ApoB.There was a significant difference between steroidal and non-steroidal in their effect on triglycerides and ApoA1.Tamoxifen had significant effects on lipids lowering cholesterol and cLDL and increasing triglycerides HDL and ApoA-1.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4086.

All-sky LIGO search for periodic gravitational waves in the early fifth-science-run data

We report on an all-sky search with the LIGO detectors for periodic gravitational waves in the frequency range 50-1100 Hz and with the frequency's time derivative in the range -5 x 10{-9}-0 Hz s{-1}. Data from the first eight months of the fifth LIGO science run (S5) have been used in this search, which is based on a semicoherent method (PowerFlux) of summing strain power. Observing no evidence of periodic gravitational radiation, we report 95% confidence-level upper limits on radiation emitted by any unknown isolated rotating neutron stars within the search range. Strain limits below 10{-24} are obtained over a 200-Hz band, and the sensitivity improvement over previous searches increases the spatial volume sampled by an average factor of about 100 over the entire search band. For a neutron star with nominal equatorial ellipticity of 10{-6}, the search is sensitive to distances as great as 500 pc.

All-sky LIGO search for periodic gravitational waves in the early fifth-science-run data

We report on an all-sky search with the LIGO detectors for periodic gravitational waves in the frequency range 50-1100 Hz and with the frequency's time derivative in the range -5 x 10{-9}-0 Hz s{-1}. Data from the first eight months of the fifth LIGO science run (S5) have been used in this search, which is based on a semicoherent method (PowerFlux) of summing strain power. Observing no evidence of periodic gravitational radiation, we report 95% confidence-level upper limits on radiation emitted by any unknown isolated rotating neutron stars within the search range. Strain limits below 10{-24} are obtained over a 200-Hz band, and the sensitivity improvement over previous searches increases the spatial volume sampled by an average factor of about 100 over the entire search band. For a neutron star with nominal equatorial ellipticity of 10{-6}, the search is sensitive to distances as great as 500 pc.

All-sky LIGO search for periodic gravitational waves in the early fifth-science-run data

We report on an all-sky search with the LIGO detectors for periodic gravitational waves in the frequency range 50-1100 Hz and with the frequency's time derivative in the range -5 x 10{-9}-0 Hz s{-1}. Data from the first eight months of the fifth LIGO science run (S5) have been used in this search, which is based on a semicoherent method (PowerFlux) of summing strain power. Observing no evidence of periodic gravitational radiation, we report 95% confidence-level upper limits on radiation emitted by any unknown isolated rotating neutron stars within the search range. Strain limits below 10{-24} are obtained over a 200-Hz band, and the sensitivity improvement over previous searches increases the spatial volume sampled by an average factor of about 100 over the entire search band. For a neutron star with nominal equatorial ellipticity of 10{-6}, the search is sensitive to distances as great as 500 pc.

All-sky LIGO search for periodic gravitational waves in the early fifth-science-run data

We report on an all-sky search with the LIGO detectors for periodic gravitational waves in the frequency range 50-1100 Hz and with the frequency's time derivative in the range -5 x 10{-9}-0 Hz s{-1}. Data from the first eight months of the fifth LIGO science run (S5) have been used in this search, which is based on a semicoherent method (PowerFlux) of summing strain power. Observing no evidence of periodic gravitational radiation, we report 95% confidence-level upper limits on radiation emitted by any unknown isolated rotating neutron stars within the search range. Strain limits below 10{-24} are obtained over a 200-Hz band, and the sensitivity improvement over previous searches increases the spatial volume sampled by an average factor of about 100 over the entire search band. For a neutron star with nominal equatorial ellipticity of 10{-6}, the search is sensitive to distances as great as 500 pc.

A randomised study comparing the effects of anastrozole and letrozole on lipid metabolism

Abstract #1152

Background:
 Aromatase inhibitors (AIs) reduce circulating oestrogen which may have a detrimental effect on lipid metabolism. Letrozole (L) decreases circulating oestrogen levels to a greater degree than anastrozole (A). This study compares the effects of adjuvant anastrozole and letrozole on lipid metabolism.
 Patients and Methods:
 This was an open, randomised pharmacodynamic study. Plasma lipids were measured in a subset of 57 out of 182 postmenopausal women with invasive ER positive breast cancer. As part of their adjuvant hormone therapy, patients were randomized to receive either
 · 12 weeks of L followed by 12 weeks of A (L→A) or
 · 12 weeks of A followed by 12 weeks of L (A→L).
 Fasting blood and urine samples were collected at the same time of day and the same day at entry and after 12 weeks of each drug.
 · 29 had no prior tamoxifen and
 · 27 had received tamoxifen.
 The following lipoproteins were measured:
 - Triglyceride - HDL
 - Cholesterol - ApoA1
 - ApoB
 - Cholesterol
 - cLDL
 HDL and ApoA1 are cardioprotective whereas ↑ levels of the others are associated with an ↑ risk of coronary artery disease.
 Results:
 (Expressed as absolute changes +/- 95% CI)
 Patients who stopped tamoxifen >12 weeks prior to trial entry were considered tamoxifen free. Patients who had stopped tamoxifen <12 weeks prior to trial entry were considered to have tamoxifen in their system at trial entry.
 A vs L: 
 There were no significant differences detected between A and L.
 A vs L in tamoxifen vs no tamoxifen groups:
 Triglycerides. Both A and L resulted in a significant decrease in triglycerides in patients who had tamoxifen in their systems, A = -0.02 (-0.24, 0.20) and L = 0.08 (-0.13, 0.29) vs those with no prior tamoxifen A = 0.51 (0.35, 0.68) and L = 0.56 (0.39, 0.72). A p = 0.0003 and L p = 0.001 respectively.
 ApoB. Both A and L resulted in a significant decrease in ApoB in patients who had tamoxifen in their systems, A = 0.78 (0.64, 0.91) and L = 0.84 (0.71, 0.97) vs those with no prior tamoxifen A = 0.92 (0.82, 1.02) and L = 0.91 (0.80, 1.01). p = 0.03 for both drugs.
 HDL. A resulted in a significant increase in HDL in patients who had tamoxifen in their systems 1.68 (1.49, 1.86) vs those with no prior tamoxifen 1.38 (1.24, 1.53) p = 0.02.
 There were no significant changes for any other variables measured.
 Conclusions:
 There were no significant differences between letrozole and anastrozole in their effects on lipids.
 Patients who had recently completed tamoxifen and commenced anastrozole or letrozole showed beneficial changes in their lipid profile compared to patients with no tamoxifen in their systems.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1152.

A randomised study comparing the effects of anastrozole (A), letrozole (L), exemestane (E) and tamoxifen (T) on coagulation

Abstract #1132

Background:
 Aromatase inhibitors (AIs) reduce circulating oestrogens and so should have either no or a positive effect on coagulation . This study compares the effects of the non-steroidal aromatase inhibitors, A and L and the steroidal inactivator, E on coagulation.
 Patients and Methods:
 This was an open, randomized pharmacodynamic study. Plasma coagulation factors were measured in 120 postmenopausal women with invasive ER +ve breast cancer. As part of their adjuvant hormone therapy, patients were randomized to receive upfront therapy with either:
 16 weeks of A, 16 weeks of L or 16 weeks of E.
 Fasting blood samples were collected at entry and after 12 and 16 weeks of each drug. AI patients were then switched to T and further samples measured after 8 months on T.
 Plasminogen activator inhibitor (PAI) antigen, von Willebrand's Factor (vWF) antigen, antithrombin III (AT111), protein C, protein S total, protein S free, activated protein C, resistance (APCR), factor VIII and fibrinogen were measured.
 Results:
 Results expressed as % change from baseline.
 E vs A vs L
 Protein C. E caused a significant fall compared to A and L (-15.75 (-21.48, -10.02) vs -3.80 (-10.77, 3.16) vs -3.63 (-10.50, 3.25)) respectively. p = 0.008.
 ATIII. E caused a significant fall from baseline (-8.55 (-13.33, -3.79))
 Protein S Free. E + A caused a significant increase from baseline (E 6.90 (1.98, 11.82), A 7.36 (1.37, 13.34).
 Steroidal vs non-steroidal:
 Protein C. A significantly greater fall was seen with E than A+L (-15.75 (-21.45, -10.05) vs -3.71 (-8.58, 1.15)) p = 0.002.
 vWF A+L caused a significant increase from baseline (6.52 (0.66, 12.38) but this was not statistically different to E 5.02 (-1.88, 11.91)).
 ATIII A significant decrease from baseline was seen with A + L, -4.54 (-8.64, -0.43) but no difference from E 8.55 (13.31, -3.70) p=0.21.
 Protein S Free There was a significant increase from baseline in both groups (A+L: 5.70 (1.47, 9.92), E: 6.90 (1.98, 11.81), but no difference between the groups p=0.72.
 T effect:
 AT111 and protein C levels fell significantly on T whereas protein S free increased on T. Prior A, E or L had no significant impact on post-tamoxifen results.
 Conclusions:
 No significant differences in any coagulation factors were seen between A and L
 E caused a significant fall in protein C and ATIII.
 The non-steroidal AIs caused a significant increase in vWF.
 T caused a significant fall in protein C and ATIII and a significant increase in protein S free.
 No AI significantly influenced post-tamoxifen results.
 These drugs have significant effects on coagulation which helps to explain their clinical effects on thrombotic and thromboembolic disease.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1132.

Search for gravitational-wave bursts from soft gamma repeaters

We present a LIGO search for short-duration gravitational waves (GWs) associated with soft gamma ray repeater (SGR) bursts. This is the first search sensitive to neutron star f modes, usually considered the most efficient GW emitting modes. We find no evidence of GWs associated with any SGR burst in a sample consisting of the 27 Dec. 2004 giant flare from SGR 1806-20 and 190 lesser events from SGR 1806-20 and SGR 1900+14. The unprecedented sensitivity of the detectors allows us to set the most stringent limits on transient GW amplitudes published to date. We find upper limit estimates on the model-dependent isotropic GW emission energies (at a nominal distance of 10 kpc) between 3x10;{45} and 9x10;{52} erg depending on waveform type, detector antenna factors and noise characteristics at the time of the burst. These upper limits are within the theoretically predicted range of some SGR models.

Letrozole suppresses plasma oestradiol (E2) levels more completely than anastrozole in postmenopausal women with breast cancer

552

Background: Letrozole (L) is a more potent aromatase inhibitor in vitro than anastrozole (A). One study in 12 patients showed that in patients L provides more complete inhibition of whole body aromatase and suppression of estrone sulphate levels than A but L did not significantly suppress E2 levels more than A possibly because of the small size of the study and the difficulty of measuring E2 in postmenopausal women (Geisler et al, JCO, 20, 751, 2002). The current aim was to conduct a much larger study to determine whether 2.5mg L suppresses E2 significantly more than 1mg A and if so in what proportion of patients this is the case. Methods: 54 postmenopausal women with invasive estrogen receptor positive breast cancer were randomised as part of their adjuvant hormone therapy to receive either: 12 weeks of L followed by 12 weeks of A (L→A) or 12 weeks of A followed by 12 weeks of L (A→L). Blood for hormones were taken at the same time of the day before and after 12 weeks of each drug. E2 was measured by a highly sensitive radioimmunoassay (Dowsett et al, Cancer Res 1987;47:1957–61) with a formal detection limit of 3pmol/l. In this study we also quantified values by extrapolation below this limit. Results: 27 patients had L→A and 27 A→L. Baseline E2 levels varied from 3 to 91 pmol/l with a median of 26 pmol/l. Only 1of 54 (2%) patients had an E2 value ≥ 3pmol/l after L compared with 20 of 54 (37%) after A(p <0.000005). After extrapolation, mean E2 level after A was 2.91 (SEM 0.18) pmol/l with a median of 2.70 pmol/l and after L was 1.76 (SEM 0.10) pmol/l with a median of 1.70 pmol/l (p<0.0001). Mean residual estradiol was 9.2% of baseline with A and 5.6% with L. Conclusions: This study has demonstrated unequivocally that the more complete inhibition of aromatase achieved by 2.5mg of letrozole than 1mg of anastrozole results in a greater degree of suppression of E2, the most bioactive oestrogen.

[Table: see text]

Upper limits on a stochastic background of gravitational waves

The Laser Interferometer Gravitational-Wave Observatory has performed a third science run with much improved sensitivities of all three interferometers. We present an analysis of approximately 200 hours of data acquired during this run, used to search for a stochastic background of gravitational radiation. We place upper bounds on the energy density stored as gravitational radiation for three different spectral power laws. For the flat spectrum, our limit of omega0 < 8.4 x 10(-4) in the 69-156 Hz band is approximately 10(5) times lower than the previous result in this frequency range.

Predicting prolonged fetal heart rate deceleration following intrathecal fentanyl/bupivacaine

BACKGROUND

Intrathecal opioids for labor analgesia are occasionally associated with fetal heart rate abnormalities. We wanted to identify risk factors for this occurrence.

METHODS

The fetal tracings of 151 consecutive patients were reviewed for the period including 30 min before and 60 min after combined spinal-epidural analgesia using intrathecal bupivacaine with fentanyl. Their progress of labor at injection was also recorded.

RESULTS

Lack of fetal head engagement (odds ratio 5.5, 95% CI 2.1-14.2) and the presence of variable fetal heart rate decelerations (odds ratio 3.6, 95% CI 1.6-8.4) were associated with prolonged fetal heart rate deceleration after combined spinal-epidural analgesia.

CONCLUSION

This case-control study suggests that if the fetal head is not engaged or if the fetus is experiencing variable decelerations, there is an increased risk of prolonged fetal heart rate deceleration following intrathecal fentanyl/bupivacaine. This finding must now be confirmed in a cohort study.

Limits on gravitational-wave emission from selected pulsars using LIGO data

We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsars by a coherent multidetector analysis of the data collected during the second science run of the LIGO interferometric detectors. These are the first direct upper limits for 26 of the 28 pulsars. We use coordinated radio observations for the first time to build radio-guided phase templates for the expected gravitational-wave signals. The unprecedented sensitivity of the detectors allows us to set strain upper limits as low as a few times 10(-24). These strain limits translate into limits on the equatorial ellipticities of the pulsars, which are smaller than 10(-5) for the four closest pulsars.

Protective Responses in Tuberculosis: Induction of Genes for Interferon-gamma and Cytotoxicity by Mycobacterium tuberculosis and During Human Tuberculosis

The host effector mechanisms against Mycobacterium tuberculosis infection are not well understood, and this remains a problem in the development of new vaccines and immunotherapies in tuberculosis (TB). Here, we studied the expression of genes for interferon gamma (IFN-gamma) and molecules involved in lymphocyte-mediated cytotoxicity [granzyme B (grzB), perforin, granulysin and Fas ligand (FasL)] against M. tuberculosis-infected macrophages. The kinetics of expression of these molecules were first established in peripheral blood mononuclear cells (PBMC) of healthy donors, and then investigated in TB patients with and without HIV-1 coinfection and appropriate control groups. We found that only IFN-gamma and grzB were induced by M. tuberculosis in PBMC from healthy purified protein derivative skin test reactive subjects. However, expression of neither gene nor IFN-gamma protein correlated with intracellular M. tuberculosis growth containment by macrophages. Mycobacterium tuberculosis induction of IFN-gamma, but not grzB, mRNA expression was significantly lower (P < 0.03) in TB patients as compared with healthy subjects.

Effects of prior concentric training on eccentric exercise induced muscle damage

BACKGROUND

Exercise induced muscle damage (EIMD) from strenuous unaccustomed eccentric exercise is well documented. So too is the observation that a prior bout of eccentric exercise reduces the severity of symptoms of EIMD. This has been attributed to an increase in sarcomeres in series. Recent studies have suggested that prior concentric training increases the susceptibility of muscle to EIMD following eccentric exercise. This has been attributed to a reduction of sarcomeres in series, which decreases muscle compliance and changes the length-tension relation of muscle contraction.

OBJECTIVE

To assess the effects of prior concentric training on the severity of EIMD.

METHODS

Four men and four women (mean (SD) age 21.1 (0.8) years) followed a four week concentric training programme. The elbow flexor musculature of the non-dominant arm was trained at 60% of one repetition maximum dynamic concentric strength performance, three times a week, increasing to 70% by week 3. After three days of rest, participants performed 50 maximal isokinetic eccentric contractions on both arms. All participants gave written informed consent before taking part in this study, which was approved by the school ethics committee. Strength, relaxed arm angle (RAA), arm circumference, and soreness on active extension and flexion were recorded immediately before eccentric exercise, one hour after, and at 24 hour intervals for three days. Data were analysed with fully repeated measures analyses of variance.

RESULTS

Strength retention was significantly (p<0.01) greater in the control arm than the trained arm (84.0 (13.7)%, 90.4 (14.7)%, 95.2 (10.5)%, 103.5 (7.6)% v 75.5 (11.3)%, 77.6 (15.3)%, 80.1 (13.9)%, 80.9 (12.5)%) at one, 24, 48, and 72 hours respectively. Similarly, soreness was greater in the trained arm (0.7 (0.6), 3.1 (1.4), 3.0 (1.5), 1.9 (2.3)) than in the untrained arm (0 (0.2), 1.6 (1.3), 1.4 (0.6), 0.6 (0.4)) at one, 24, 48, and 72 hours respectively (p<0.05). Concentric training induced a significant reduction in RAA (165.2 (6.7) degrees v 157.3 (4.9) degrees ) before the eccentric exercise bout (p<0.01). This was further reduced and remained lower in the trained arm at all time points after the eccentric exercise (p<0.01). The arm circumference of the concentrically trained arm was significantly greater than baseline (p<0.05) at 72 hours (30.3 (2.9) v 29.8 (3.3) cm).

CONCLUSIONS

These findings extend the understanding of the effects of prior concentric training in increasing the severity of EIMD to an upper limb exercise model. The inclusion of concentric conditioning in rehabilitation programmes tends to exacerbate the severity of EIMD in subsequent unaccustomed exercise. However, where concentric conditioning is indicated clinically, the net effect of conditioning outcome and EIMD may still confer enhanced strength performance and capability to dynamically stabilise a joint system.

Phosphorus availability for beneficial use in biosolids products

It has become necessary to identify accurately the availability of phosphorus in biosolids products applied to land. The fertiliser value of these products must be quantified not only to satisfy the customer but also to ensure the best use of phosphorus when considering the need to avoid excess concentrations in the wider environment, With the advent of chemical phosphorus removal at more wastewater treatment works, the impact of iron and phosphate availability is particularly important. Existing research has indicated that there is a correlation between phosphate availability, and factors such as biosolids pH and iron concentration. However, it has not yet been possible to draw any firm conclusions, which can be used as a tool to manage the availability of phosphate in practice. Through a joint research programme for Anglian Water, involving literature investigation, laboratory tests on biosolid/soil interactions, and benchmarking phosphate availability over time, the study uses the best available input and output data to indicate the parts of the land bank most at risk from over-enrichment.

Augmentation of apoptosis and interferon-gamma production at sites of active Mycobacterium tuberculosis infection in human tuberculosis

Pleural tuberculosis (TB) was employed as a model to study T cell apoptosis at sites of active Mycobacterium tuberculosis (MTB) infection in human immunodeficiency virus (HIV)-coinfected (HIV/TB) patients and patients infected with TB alone. Apoptosis in blood and in pleural fluid mononuclear cells and cytokine immunoreactivities in plasma and in pleural fluid were evaluated. T cells were expanded at the site of MTB infection, irrespective of HIV status. Apoptosis of CD4 and non-CD4 T cells in the pleural space occurred in both HIV/TB and TB. Interferon (IFN)-gamma levels were increased in pleural fluid, compared with plasma. Spontaneous apoptosis correlated with specific loss of MTB-reactive, IFN-gamma-producing pleural T cells. Immunoreactivities of molecules potentially involved in apoptosis, such as tumor necrosis factor-alpha, Fas-ligand, and Fas, were increased in pleural fluid, compared with plasma. These data suggest that continued exposure of immunoreactive cells to MTB at sites of infection may initiate a vicious cycle in which immune activation and loss of antigen-responsive T cells occur concomitantly, thus favoring persistence of MTB infection.

The Children's PTSD Inventory: development and reliability

Information involving the development of the DSM-IV version of the Children's PTSD Inventory is described. Independent ratings by highly experienced judges denote that the instrument encompassed the universe of definition that it was intended to measure (i.e., the DSM-IV criteria for PTSD). The instrument was administered to 82 traumatized and 22 nontraumatized youths at Bellevue Hospital. Moderate to high Cronbach alphas (.53-.89) were evident at the subtest level. An alpha of .95 was evident at the diagnostic level. In terms of inter-rater reliability, 98.1% agreement was evident at the diagnostic level. Inter-rater intraclass correlation coefficients (ICCs) ranged from .88 to .96 at the subtest level and .98 at the diagnostic level. Good to excellent kappas (.66-1.00) were reported for inter-rater reliability at the subtest level. An inter-rater reliability kappa of .96 was evident at the diagnostic level. In terms of test-retest reliability, 97.6% agreement was evident at the diagnostic level. Good to excellent test-retest kappas (.66-1.00) and ICCs (.66-.94) were observed. A test-retest kappa of .91 and an ICC of .88 was observed at the diagnostic level.

A cluster of necrotizing enterocolitis in term infants undergoing open heart surgery

BACKGROUND

Necrotizing enterocolitis (NEC) is a serious gastrointestinal disease of unknown cause that predominantly affects premature infants, but it has been reported in term infants with congenital heart disease.

METHODS

In August and September of 1997, 4 cases of NEC in term infants with congenital heart disease were identified among 24 infants undergoing cardiac surgical procedures at our institution. Because nosocomial NEC had not previously been identified among infants in our pediatric intensive care unit, a case-control study was conducted to identify risk factors for NEC. All infants less than 4 months old undergoing cardiac surgery without development of NEC during the epidemic period were selected as controls.

RESULTS

The only significant risk factor associated with case-infants was a higher mean temperature gradient (rectal/toe) during the immediate 12-hour postoperative period (4.0 degrees C vs 2.0 degrees C, P <.01). Urine output was higher in control-infants in this postoperative period, although not statistically significant (11.9 mL/h vs 6.1 mL/h, P =.15).

CONCLUSION

Although an infectious etiology cannot be ruled out, the cases of NEC in infants with congenital heart disease after cardiac procedures may have resulted from mesenteric ischemia associated with a low perfusion state in the perioperative period.

The relationship of motor unit size, firing rate and force

OBJECTIVE

Using a clinical electromyographic (EMG) protocol, motor units were sampled from the quadriceps femoris during isometric contractions at fixed force levels to examine how average motor unit size and firing rate relate to force generation.

METHODS

Mean firing rates (mFRs) and sizes (mean surface-detected motor unit action potential (mS-MUAP) area) of samples of active motor units were assessed at various force levels in 79 subjects.

RESULTS

MS-MUAP size increased linearly with increased force generation, while mFR remained relatively constant up to 30% of a maximal force and increased appreciably only at higher force levels. A relationship was found between muscle force and mS-MUAP area (r2 = 0.67), mFR (r2 = 0.38), and the product of mS-MUAP area and mFR (mS-MUAP x mFR) (r2 = 0.70).

CONCLUSIONS

The results support the hypothesis that motor units are recruited in an orderly manner during forceful contractions, and that in large muscles only at higher levels of contraction ( > 30% MVC) do mFRs increase appreciably. MS-MUAP and mFR can be assessed using clinical EMG techniques and they may provide a physiological basis for analyzing the role of motor units during muscle force generation.

Firing rate analysis using decompostion-enhanced spike triggered averaging in the quadriceps femoris

Electromyographic signals detected from the quadriceps femoris during various constant force contractions were decomposed to identify individual motor unit discharges and mean firing rates (FRs). Subject and group mean FRs were calculated for each force level. Mean FR values and FR variability increased with force. Individual, subject, and group mean FRs showed slight increases until 30% of maximum voluntary contraction and larger increases thereafter. Findings are discussed in relation to motor unit recruitment, frequency modulation, and fatigue.

Rationalization as a key stressor for public sector employees: an organizational case study

Public sector organizations throughout Europe have been subject to cuts in Government spending, allied to demands for enhanced efficiency and effectiveness. Consequently, many have embarked upon radical programmes of change which potentially have an adverse effect upon the psychological well-being of employees. This study aimed to assess linkages between organization change and the psychological well-being of employees within the Swedish social insurance organization Försäkringskassan. A case study approach was adopted for the investigation which was carried out within the Halland region between February and June 1995. A questionnaire which included the Cultural Audit and the General Well Being Questionnaire was distributed to the organization's 456 employees in Halland. Questionnaire were returned by 246 employees (54.6%), reflecting the employment structure of the organization. The findings revealed that many issues associated with the process of rationalization and change were of concern to employees. Statistical analyses revealed that these were linked to their relatively high levels of 'anxiety' and their symptoms of being 'worn out'. This study indicates that the process of organization change is stressful for employees within Försäkringskassan. As public sector organizations throughout Europe are subject to similar pressure and are being forced to embark upon change programmes, it is suggested that they take cognizance of the findings of this investigation when making decisions regarding the planning and implementation of organization change.

Comparative analysis of smooth muscle isoactin gene expression in normal and neoplastic tissues

Monoclonal antibodies derived from the actin multigene family are routinely used as an adjunct to morphologic diagnoses of smooth muscle tumors. Northern blot analysis was performed on 60 surgical resections utilizing isoactin-specific cDNAs. A comparison of this analysis to immunohistochemical studies demonstrated that actin-specific monoclonal antibodies represent reliable markers of the smooth muscle lineage. Smooth muscle neoplasms showed a unique pattern of gamma-smooth muscle isoactin gene expression, providing a potentially valuable molecular adjunct to the morphologic diagnosis of uterine smooth muscle tumors.

Decomposition-enhanced spike-triggered averaging: contraction level effects

Decomposition-enhanced spike-triggered averaging (DE-STA) was applied to the vastus medialis muscle to examine size distributions of surface-detected motor-unit action potentials (S-MUAPs) at various force levels. Using DE-STA, 15-20 S-MUAPs were identified during 5%, 10%, 20%, and 30% of maximum voluntary contraction. Average S-MUAPs showed increase in peak to peak (and negative peak) amplitude with force (In microV): 5% = 37.9 +/- 6.1 (16.6 +/- 2.5), 10% = 44.0 +/- 4.0 (20.4 +/- 1.8), 20% = 80.7 +/- 9.3 (41.3 +/- 4.5), and 30% = 102.5 +/- 10.3 (53.6 +/- 5.0). Test-retest variability of peak to peak (and negative peak amplitude) between repeated trials was 0.10 (0.14), 0.14 (0.14), 0.17 (0.15), and 0.21 (0.20) at 5%, 10%, 20%, and 30% respectively. A relationship was found between the S-MUAP amplitude and force (r2 = 0.78, df = 90, F = 160, P < 0.001). Increase in average S-MUAP amplitude with force suggests that STA performed only at low levels of contraction may result in a biased sampling and small average S-MUAP amplitudes.

Molecular determination of the malignant potential of smooth muscle neoplasms

BACKGROUND

The determination of the malignant potential of smooth muscle neoplasms remains ambiguous, and yet has far reaching clinical, therapeutic, and social implications.

METHODS

In this pilot study, the authors examined smooth muscle isoactin gene expression by polymerase chain reaction in a variety of smooth muscle tumors.

RESULTS

A lack of gamma-smooth muscle isoactin gene expression correlated 100% with a pathologic diagnosis of sarcoma. These results suggest that gamma-smooth muscle isoactin gene expression represents a unique molecular marker of oncogenic transformation.

CONCLUSIONS

gamma-Smooth muscle isoactin gene expression provides a valuable molecular adjunct to the diagnosis of smooth muscle neoplasms.

Immunohistochemical localization of p21(WAF1/CIP1) in normal, hyperplastic, and neoplastic uterine tissues

p21WAF1/CIP1 is a nuclear protein that binds to cyclin-dependent kinase complexes (CDKs) and inhibits the activity of multiple kinases. These CDKs are involved in the regulation of cell cycle progression at several checkpoints. In this study, the authors have analyzed by immunohistochemistry the expression of p21WAF1/CIP1 in normal uterine tissues, 12 endometrial hyperplasias, 17 endocervical adenocarcinomas, and 31 endometrial adenocarcinomas. In addition, a group of 10 leiomyomas and 10 uterine leiomyosarcomas were also stained. To evaluate cell proliferation, the monoclonal antibody Ki-67 was used in all of the available cases. Terminally differentiated epithelial endocervical and endometrial cells showed variable expression of p21WAF1/CIP1, whereas the endometrial hyperplasias, and endocervical and endometrial adenocarcinomas showed decreased expression or were negative. All of the cases of cervical squamous dysplasia were positive. Normal smooth muscle cells and 50% of leiomyomas were negative, whereas all leiomyosarcomas showed expression of p21WAF1/CIP1. These results indicate that p21WAF1/CIP1 contributes to differentiation in normal endometrial and endocervical glands. The decreased expression of p21WAF1/CIP1 in endometrial hyperplasias and carcinomas may be important in the process of neoplastic transformation. The role of certain CDK inhibitors, such as p21WAF1/CIP1, is different in epithelial and mesenchymal tumorigenesis in the uterus.