Cosmic dust impacts on the Hubble Space Telescope.

Exposure of the Hubble Space Telescope to space in low Earth orbit resulted in numerous hypervelocity impacts by cosmic dust (micrometeoroids) and anthropogenic particles (orbital debris) on the solar arrays and the radiator shield of the Wide Field and Planetary Camera 2, both subsequently returned to Earth. Solar cells preserve residues from smaller cosmic dust (and orbital debris) but give less reliable information from larger particles. Here, we present images and analyses from electron, ion and X-ray fluorescence microscopes for larger impact features (millimetre- to centimetre-scale) on the radiator shield. Validated by laboratory experiments, these allow interpretation of composition, probable origin and likely dimensions of the larger impactors. The majority (~90%) of impacts by grains greater than 50 µm in size were made by micrometeoroids, dominated by magnesium- and iron-rich silicates and iron sulfides, metallic iron-nickel and chromium-rich spinel similar to that in ordinary chondrite meteorites of asteroid origin. Our re-evaluation of the largest impact features shows substantially fewer large orbital debris impacts than reported by earlier authors. Mismatch to the NASA ORDEM and ESA MASTER models of particle populations in orbit may be partly due to model overestimation of orbital debris flux and underestimation of larger micrometeoroid numbers. This article is part of the theme issue 'Dust in the Solar System and beyond'.

A unique CO-like micrometeorite hosting an exotic Al-Cu-Fe-bearing assemblage - close affinities with the Khatyrka meteorite.

We report the discovery of a unique micrometeorite, containing an exotic Al-Cu-Fe alloy composed of two intermixed phases: khatyrkite (CuAl2) and stolperite (CuAl) and both containing minor Fe (<1.4 wt%). These phases are dendritic and rapidly co-crystallized at the binary system's peritectic (~550 °C). The host micrometeorite is an otherwise typical S-type micro-porphyritic cosmic spherule containing relict olivine (Fo76-90, Cr2O3: 0.01-0.56 wt%, MnO: 0.03-0.32 wt% and CaO: 0.09-0.22 wt%) and a cumulate layered texture. These properties suggest the micrometeorite is derived from a carbonaceous chondrite (best matched to a CO chondrite) and entered the atmosphere a high speed (~16 kms-1), implying an origin from a highly eccentric orbit. This particle represents the second independent discovery of naturally occurring intermetallic Al-Cu-Fe alloys and is thus similar to the previously reported Khatyrka meteorite - a CV chondrite containing near-identical alloys and the only known natural quasicrystals. We did not observe quasicrystalline phases in this micrometeorite, likely due to the low amounts of Fe in the alloy, insufficient to stabilize quasicrystals. Our discovery confirms the existence of Al-Cu-Fe intermetallic alloys on chondritic parent bodies. These unusual phases require a currently unexplained formation process, we tentatively suggest this could represent the delivery of exotic interstellar material to the inner solar system via impact.

One-year outcomes after successful chronic total occlusion percutaneous coronary intervention: The impact of dissection re-entry techniques.

We aimed to determine clinical outcomes 1 year after successful chronic total occlusion (CTO) PCI and, in particular, whether use of dissection and re-entry strategies affects clinical outcomes. Hybrid approaches have increased the procedural success of CTO percutaneous coronary intervention (PCI) but longer-term outcomes are unknown, particularly in relation to dissection and re-entry techniques. Data were collected for consecutive CTO PCIs performed by hybrid-trained operators from 7 United Kingdom (UK) centres between 2012 and 2014. The primary endpoint (death, myocardial infarction, unplanned target vessel revascularization) was measured at 12 months along with angina status. One-year follow up data were available for 96% of successful cases (n = 805). In total, 85% of patients had a CCS angina class of 2-4 prior to CTO PCI. Final successful procedural strategy was antegrade wire escalation 48%; antegrade dissection and re-entry (ADR) 21%; retrograde wire escalation 5%; retrograde dissection and re-entry (RDR) 26%. Overall, 47% of CTOs were recanalized using dissection and re-entry strategies. During a mean follow up of 11.5 ± 3.8 months, the primary endpoint occurred in 8.6% (n = 69) of patients (10.3% (n = 39/375) in DART group and 7.0% (n = 30/430) in wire-based cases). The majority of patients (88%) had no or minimal angina (CCS class 0 or 1). ADR and RDR were used more frequently in more complex cases with greater disease burden, however, the only independent predictor of the primary endpoint was lesion length. CTO PCI in complex lesions using the hybrid approach is safe, effective and has a low one-year adverse event rate. The method used to recanalize arteries was not associated with adverse outcomes. © 2017 Wiley Periodicals, Inc.

Hybrid approach improves success of chronic total occlusion angioplasty.

OBJECTIVES: Treatment options for coronary chronic total occlusions (CTO) are limited, with low historical success rates from percutaneous coronary intervention (PCI). We report procedural outcomes of CTO PCI from 7 centres with dedicated CTO operators trained in hybrid approaches comprising antegrade/retrograde wire escalation (AWE/RWE) and dissection re-entry (ADR/RDR) techniques. METHODS: Clinical and procedural data were collected from consecutive unselected patients with CTO between 2012 and 2014. Lesion complexity was graded by the Multicentre CTO Registry of Japan (J-CTO) score, with ≥2 defined as complex. Success was defined as thrombolysis in myocardial infarction 3 flow with <30% residual stenosis, subclassified as at first attempt or overall. Inhospital complications and 30-day major adverse cardiovascular events (MACEs, death/myocardial infarction/unplanned target vessel revascularisation) were recorded. RESULTS: 1156 patients were included. Despite high complexity (mean J-CTO score 2.5±1.3), success rates were 79% (first attempt) and 90% (overall) with 30-day MACE of 1.6%. AWE was highly effective in less complex lesions (J-CTO ≤1 94% success vs 79% in J-CTO score ≥2). ADR/RDR was used more commonly in complex lesions (J-CTO≤1 15% vs J-CTO ≥2 56%). Need for multiple approaches during each attempt increased with lesion complexity (17% J-CTO ≤1 vs 48% J-CTO ≥2). Lesion modification ('investment procedures') at the end of unsuccessful first attempts increased the chance of subsequent success (96% vs 71%). CONCLUSIONS: Hybrid-trained operators can achieve overall success rates of 90% in real world practice with acceptable MACE. Use of dissection re-entry and investment procedures maintains high success rates in complex lesions. The hybrid approach represents a significant advance in CTO treatment.

Impact of proctoring on success rates for percutaneous revascularisation of coronary chronic total occlusions.

OBJECTIVE: To assess the impact of proctoring for chronic total occlusion (CTO) percutaneous coronary intervention (PCI) in six UK centres. METHODS: We retrospectively analysed 587 CTO procedures from six UK centres and compared success rates of operators who had received proctorship with success rates of the same operators before proctorship (pre-proctored) and operators in the same institutions who had not been proctored (non-proctored). There were 232 patients in the pre-proctored/non-proctored group and 355 patients in the post-proctored group. Complexity was assessed by calculating the Japanese CTO (JCTO) score for each case. RESULTS: CTO PCI success was greater in the post-proctored compared with the pre-proctored/non-proctored group (77.5% vs 62.1%, p<0.0001). In more complex cases where JCTO≥2, the difference in success was greater (70.7% vs 49.5%, p=0.0003). After proctoring, there was an increase in CTO PCI activity in centres from 2.5% to 3.5%, p<0.0001 (as a proportion of total PCI), and the proportion of very difficult cases with JCTO score ≥3 increased from 15.3% (35/229) to 29.7% (105/354), p<0.0001. CONCLUSIONS: Proctoring resulted in an increase in procedural success for CTO PCI, an increase in complex CTO PCI and an increase in total CTO PCI activity. Proctoring may be a valuable way to improve access to CTO PCI and the likelihood of procedural success.

Cardiovascular collapse post chronic total occlusion percutaneous coronary intervention due to a compressive left atrial hematoma managed with percutaneous drainage.

This case illustrates a potential complication of the retrograde approach using epicardial collaterals for chronic total occlusion (CTO) percutaneous coronary intervention (PCI). Hypotension post CTO PCI in a patient who has undergone previous cardiac surgery can have multiple causes, one of which is chamber compression from a localized hematoma due to coronary perforation as occurred in this case. This report is the first description of successful nonsurgical management of a left atrial hematoma causing cardiovascular collapse with percutaneous drainage.

Urgent in-patient coronary angiography: a comparison of centres with and without cardiac catheter facilities.

OBJECTIVES: To review the referral of patients to a tertiary centre for urgent angiography and to determine if there are differences in invasive treatment strategies for patients with acute coronary syndrome (ACS). METHODS: There were 2 parts to the study, a retrospective part over 3.5 years from a computerised cardiac laboratory booking data base and a prospective part over 3 months. RESULTS: There were 1190 urgent in-patient angiograms performed with 499 (42%) admitted initially to the tertiary centre while the remaining 691 (58%) were admitted to district general hospitals (DGH), with no on-site access to a cardiac laboratory, and subsequently transferred to the tertiary centre. Once referred, DGH patients waited longer for their angiogram (2.7 +/- 3.2 vs 2.0 +/- 2.8 days, p < 0.0001). Interestingly, DGH patients appear to spend an average of 4 days in hospital prior to referral for angiography. DGH patients were more likely to have a higher Thrombosis in Myocardial Infarction (TIMI) risk score at presentation and following angiography were more likely to have coronary artery bypass graft (CABG) or percutaneous coronary intervention (PCI) and less likely to have angiographically normal arteries. CONCLUSIONS: Our findings are consistent with previous studies demonstrating that access to coronary angiography varies considerably between hospitals. However, we have demonstrated that patients in DGHs wait on average 4 days before referral for coronary angiography suggesting that there may be triage based on initial responses to medical therapy. Further research is needed to determine whether this has a direct effect on outcomes.

Crustal rheology of the Himalaya and Southern Tibet inferred from magnetotelluric data.

The Cenozoic collision between the Indian and Asian continents formed the Tibetan plateau, beginning about 70 million years ago. Since this time, at least 1,400 km of convergence has been accommodated by a combination of underthrusting of Indian and Asian lithosphere, crustal shortening, horizontal extrusion and lithospheric delamination. Rocks exposed in the Himalaya show evidence of crustal melting and are thought to have been exhumed by rapid erosion and climatically forced crustal flow. Magnetotelluric data can be used to image subsurface electrical resistivity, a parameter sensitive to the presence of interconnected fluids in the host rock matrix, even at low volume fractions. Here we present magnetotelluric data from the Tibetan-Himalayan orogen from 77 degrees E to 92 degrees E, which show that low resistivity, interpreted as a partially molten layer, is present along at least 1,000 km of the southern margin of the Tibetan plateau. The inferred low viscosity of this layer is consistent with the development of climatically forced crustal flow in Southern Tibet.

Direct comparison of selective endothelin A and non-selective endothelin A/B receptor blockade in chronic heart failure.

OBJECTIVE: To investigate the potential differential effects of selective endothelin (ET) A and dual ET-A/B receptor blockade in patients with chronic heart failure. METHODS: Nine patients with chronic heart failure (New York Heart Association class II-III) each received intravenous infusions of BQ-123 alone (selective ET-A blockade) and combined BQ-123 and BQ-788 (dual ET-A/B blockade) in a randomised, placebo controlled, three way crossover study. RESULTS: Selective ET-A blockade increased cardiac output (maximum mean (SEM) 33 (12)%, p < 0.001) and reduced mean arterial pressure (maximum -13 (4)%, p < 0.001) and systemic vascular resistance (maximum -26 (8)%, p < 0.001), without changing heart rate (p = 0.38). Dual ET-A/B blockade significantly reduced the changes in all these haemodynamic variables compared with selective ET-A blockade (p < 0.05). Selective ET-A blockade reduced pulmonary artery pressure (maximum 25 (7)%, p = 0.01) and pulmonary vascular resistance (maximum 72 (39)%, p < 0.001). However, there was no difference between these effects and those seen with dual ET-A/B blockade. Unlike selective ET-A blockade, dual ET-A/B blockade increased plasma ET-1 concentrations (by 47 (4)% with low dose and 61 (8)% with high dose, both p < 0.05). CONCLUSIONS: While there appeared to be similar reductions in pulmonary pressures with selective ET-A and dual ET-A/B blockade, selective ET-A blockade caused greater systemic vasodilatation and did not affect ET-1 clearance. In conclusion, there are significant haemodynamic differences between selective ET-A and dual ET-A/B blockade, which may determine responses in individual patients.

The role of diagnostic radiology in compressive and entrapment neuropathies.

Diagnostic imaging is increasingly being utilised to aid the diagnosis of compression and entrapment neuropathies. Cross-sectional imaging, primarily ultrasound and magnetic resonance imaging, can provide exquisite anatomical detail of peripheral nerves and the changes that may occur as a result of compression. Imaging can provide a useful diagnostic aid to clinicians, which may supplement clinical evaluation, and may eventually provide an alternative to other diagnostic techniques such as nerve conduction studies. This article describes the abnormalities that may be demonstrated by current imaging techniques, and critically analyses the impact of imaging in diagnosis of peripheral compressive neuropathy.

Systemic ETA receptor antagonism with BQ-123 blocks ET-1 induced forearm vasoconstriction and decreases peripheral vascular resistance in healthy men.

1. The effect on systemic haemodynamics of BQ-123, a selective endothelin A (ETA) receptor antagonist, was investigated in healthy men by giving, on separate occasions, ascending intravenous doses of 100, 300, 1000 and 3000 nmol min(-1) BQ-123, each for 15 min, in a randomized, placebo-controlled, double-blind study. The response of forearm blood flow to brachial artery infusion of endothelin-1 (ET-1; 5 pmol min(-1) for 90 min) was also studied using bilateral forearm plethysmography, after systemic pre-treatment, on separate occasions, with one of two doses of BQ-123 (300 and 1000 nmol min(-1) for 15 min) or placebo. 2. Systemic BQ-123 dose-dependently decreased systemic vascular resistance (P<0.01 for all doses vs placebo) and mean arterial pressure (P<0.05 for 300 nmol min(-1) and P<0.01 for 1000 and 3000 nmol min(-1)) during the 60 min following infusion. There were concurrent increases in heart rate and cardiac index. BQ-123, when infused systemically for 15 min, appeared to reach a maximum effect at 1000 nmol min(-1). 3. Intra-brachial ET-1 infusion, after pre-treatment with placebo, caused a slow onset progressive forearm vasoconstriction without systemic effects. This vasoconstriction was attenuated by pre-treatment with BQ-123 at 300 nmol min(-1) and abolished by BQ-123 at 1000 nmol min(-1) (P<0.01 vs placebo). 4. These effects occurred at concentrations of BQ-123 in the plasma (510+/-64 nmol l(-1)) that were ETA receptor selective, and were not accompanied by an increase in plasma ET-1 that would have indicated ETB receptor blockade. 5. We conclude that ETA-mediated vascular tone contributes to the maintenance of basal systemic vascular resistance and blood pressure in healthy men.

Priming by DNA immunization augments protective efficacy of Mycobacterium bovis Bacille Calmette-Guerin against tuberculosis.

Sequential immunization with mycobacterial antigen Ag85B-expressing DNA and Mycobacterium bovis bacille Calmette-Guerin (BCG) was more effective than BCG immunization in protecting against Mycobacterium tuberculosis infection. Depletion of the CD8(+) T cells in the immunized mice impaired protection in their spleens, indicating that this improved efficacy was partially mediated by CD8(+) T cells.