Picometre-precision analysis of scanning transmission electron microscopy images of platinum nanocatalysts.

Measuring picometre-scale shifts in the positions of individual atoms in materials provides new insight into the structure of surfaces, defects and interfaces that influence a broad variety of materials' behaviour. Here we demonstrate sub-picometre precision measurements of atom positions in aberration-corrected Z-contrast scanning transmission electron microscopy images based on the non-rigid registration and averaging of an image series. Non-rigid registration achieves five to seven times better precision than previous methods. Non-rigidly registered images of a silica-supported platinum nanocatalyst show pm-scale contraction of atoms at a (111)/(111) corner towards the particle centre and expansion of a flat (111) facet. Sub-picometre precision and standardless atom counting with <1 atom uncertainty in the same scanning transmission electron microscopy image provide new insight into the three-dimensional atomic structure of catalyst nanoparticle surfaces, which contain the active sites controlling catalytic reactions.

Management of patients taking antiplatelet or anticoagulant medication requiring invasive breast procedures: United Kingdom survey of radiologists' and surgeons' current practice.

AIM: To determine the current practice in the UK National Health Service Breast Screening Programme for invasive diagnostic procedures and surgery in patients taking anticoagulant and antiplatelet medication. MATERIALS AND METHODS: Lead radiologists and surgeons at each breast screening service were surveyed to determine current practice. One hundred and five respondents provided information regarding their services, protocols, and willingness to proceed with combinations of procedures and anti-haemostatic medications. RESULTS: Between units there was wide variation in practice. Within 21 services providing more than one response, 10 (48%) disagreed on whether protocols existed. Decisions to perform biopsies were unrelated to professional group. The taking of a drug history was variable. Surgeons reported more adverse effects than radiologists [21 (48%) versus 12 (26%)], but no difference in self-assessment of knowledge. CONCLUSION: Both radiologists and surgeons have expressed uncertainty about their understanding of anticoagulant and antiplatelet treatment. This is reflected in a wide range of practice. Guidance regarding the management of these patients is suggested.

Mammotome biopsy: impact on preoperative diagnosis rate.

AIM: To assess the impact of mammotome biopsy on preoperative diagnosis rate. METHODS: A prospective study was undertaken to examine the referral patterns, radiological abnormalities, sensitivity, specificity and outcome of the first 150 patients undergoing mammotome biopsy at our institution. Most of the referrals were from the NHS Breast Screening Programme (85/100). RESULTS: The commonest radiological abnormality was microcalcification (87%). The accuracy of this biopsy technique for the target lesion was over 99%. Post-biopsy, 11 patients needed to proceed to a diagnostic surgical biopsy (7%). Forty-two malignancies were identified at final histology; 41 were diagnosed preoperatively. The positive predictive of mammotome biopsy was 98% for the present study. The present results for mammotome biopsy with regard to predicting invasion were: sensitivity 71.4% (10/14); specificity 100% (0/0); positive predictive value 100% (10/10); and negative predictive value 87% (27/31). CONCLUSION: Prone mammotome biopsy has proven to be highly accurate, considerably improving the preoperative diagnosis within our unit, and obviating the majority of diagnostic excision biopsies.

Imaging features of breast trauma: a pictorial review.

Accidental injury to the female breast can cause symptoms and signs which may mimic carcinoma and can also be painful or disfiguring. Nine women who sustained injury to the breast are presented, illustrating some of the manifestations of traumatic injury to the female breast, the majority of which are attributable to fat necrosis. A brief discussion of the clinical and imaging features of fat necrosis is included. These cases reinforce the importance of triple assessment in any woman presenting with a breast lump, even with a clear history of trauma.

The diagnosis of invasive lobular breast carcinoma. Does MRI have a role?

Invasive lobular breast carcinoma accounts for approximately 15% of all breast cancers and is difficult to detect using conventional breast imaging techniques. We report a comparison between clinical, ultrasound scan (USS), mammographic and magnetic resonance imaging (MRI) of 22 patients with invasive lobular breast carcinomas. Actual tumour size was ascertained by histopathology. MRI detected 21 of the 22 invasive lobular cancers whilst mammography and USS detected 16 and 20 respectively. 19 tumours were clinically palpable. MRI was more accurate at assessing tumour size than USS and clinical examination, both of which underestimated tumour size.

Z-contrast imaging of supported Pt and Pd clusters.

High-angle annular dark-field or Z-contrast microscopy was used to demonstrate that well dispersed metal supported catalysts consist of nanometer sized clusters. Depending upon the impregnated metal, different cluster sizes were observed. Grouping of Pd clusters could also be confirmed by analytical electron microscopy.

Proton-linked L-rhamnose transport, and its comparison with L-fucose transport in Enterobacteriaceae.

1. An alkaline pH change occurred when L-rhamnose, L-mannose or L-lyxose was added to L-rhamnose-grown energy-depleted suspensions of strains of Escherichia coli. This is diagnostic of sugar-H+ symport activity. 2. L-Rhamnose, L-mannose and L-lyxose were inducers of the sugar-H+ symport and of L-[14C]rhamnose transport activity. L-Rhamnose also induced the biochemically and genetically distinct L-fucose-H+ symport activity in strains competent for L-rhamnose metabolism. 3. Steady-state kinetic measurements showed that L-mannose and L-lyxose were competitive inhibitors (alternative substrates) for the L-rhamnose transport system, and that L-galactose and D-arabinose were competitive inhibitors (alternative substrates) for the L-fucose transport system. Additional measurements with other sugars of related structure defined the different substrate specificities of the two transport systems. 4. The relative rates of H+ symport and of sugar metabolism, and the relative values of their kinetic parameters, suggested that the physiological role of the transport activity was primarily for utilization of L-rhamnose, not for L-mannose or L-lyxose. 5. L-Rhamnose transport into subcellular vesicles of E. coli was dependent on respiration, was optimal at pH 7, and was inhibited by protonophores and ionophores. It was insensitive to N-ethylmaleimide or cytochalasin B. 6. L-Rhamnose, L-mannose and L-lyxose each elicited an alkaline pH change when added to energy-depleted suspensions of L-rhamnose-grown Salmonella typhimurium LT2, Klebsiella pneumoniae, Klebsiella aerogenes, Erwinia carotovora carotovora and Erwinia carotovora atroseptica. The relative rates of subsequent acidification varied, depending on both the organism and the sugar. L-Fucose promoted an alkaline pH change in all the L-rhamnose-induced organisms except the Erwinia species. No L-rhamnose-H+ symport occurred in any organism grown on L-fucose. 7. All these results showed that L-rhamnose transport into the micro-organisms occurred by a system different from that for L-fucose transport. Both systems are energized by the trans-membrane electrochemical gradient of protons. 8. Neither steady-state kinetic measurements nor binding-protein assays revealed the existence of a second L-rhamnose transport system in E. coli.

Computed tomographic assessment of soft tissue abnormalities following calcaneal fractures.

Computed tomographic (CT) examinations of 50 acute calcaneal fractures were compared with a further series of 77 fractures in which the date of injury preceded the CT by 6 months or more. 42 (84%) of the fractures in the acute group and 55 (71%) in the chronic group were classified as intra-articular and they form the basis of this study. The alteration in the position of the peroneal tendons in the two groups was similar, with a 5% or less difference in each category. In the acute group the peroneal tendons were normally located in 40.4% of the cases, entrapped by bone in 11.9%, subluxed in 33.3% and dislocated in 14.2%. Structural abnormalities of the peroneal tendons and surrounding soft tissues were identified in 52.4% of the acute group and in 61.1% of the chronic group. The incidence of partial rupture of the peroneal tendons in the chronic group was approximately one third that in the acute group, but the low incidence of complete tendon rupture remained unchanged. The inference from these observations is that, in the majority of cases, partial peroneal tendon rupture is reversible, whereas complete rupture is not. Seven fractures were common to both series and from this limited group the identification of haemorrhage around the peroneal tendons in the acute phase was shown not to be related to the subsequent development of chronic stenosing tenosynovitis. Various abnormalities of the medial tendons of the hindfoot were identified in 17% of the acute group and in 18% of the chronic group. Following calcaneal fracture, CT in both the immediate post-fracture period and in the late phase can be used to detect and classify the soft tissue changes. The limitations of comparing the two groups in this study are discussed.

Air aspiration after double-contrast knee arthrography: a worthwhile exercise?

A prospective study following double-contrast knee arthrography was undertaken to compare pain and discomfort experienced at the conclusion of the procedure and for 7 days afterwards. The patients were divided into two groups. Half had the air aspirated at the end of the examination and the other half did not. Twice as many patients in the aspirated group were totally asymptomatic (48% compared with 22%); however, by 7 days after the procedure the numbers of asymptomatic patients were similar in the two groups (64% and 63%, respectively). Thus our conclusion is that air aspiration after double-contrast knee arthrography does reduce short-term morbidity.

Iliac insufficiency fractures.

Twenty-five post-menopausal women with one or more insufficiency fractures of the pelvic ring are reported. In 80% of cases the fractures were multiple and a total of 79 insufficiency fractures was identified. Twelve iliac insufficiency fractures were present in 11 patients located at one of three sites: above and parallel to the acetabular roof ("supra-acetabular"), extending diagonally across the iliac ala from the greater sciatic notch ("oblique iliac"), and adjacent to the sacro-iliac joint ("superomedial iliac"). The plain radiographic appearances of these iliac fractures were typically subtle with ill defined medullary sclerosis, due to trabecular compression, the cardinal sign. Scintigraphy revealed the fractures as foci of increased activity which, in the presence of multiple pelvic insufficiency fractures, may be mistaken for metastatic disease. Computed tomography can be helpful in confirming the presence of suspected fractures, revealing further occult fractures and also excluding the likelihood of malignancy.

Computed tomographic assessment of old calcaneal fractures.

Prolonged pain and disability are common complications of calcaneal fractures. A prospective study was conducted on the value of computed tomography (CT) in 63 patients with 73 calcaneal fractures sustained more than 6 months before. The fractures were classified from the initial plain radiographs, and the patients' current clinical condition assessed in terms of a "disability score". The mean disability scores (MDS) associated with the different types of fracture were correlated with the CT findings. The highest MDS was found in the intra-articular fracture group which comprised 71% of the series. In this group the MDS was increased in the presence of post-traumatic osteoarthrosis of the subtalar joint (61% of cases), involvement of the calcaneocuboid joint (39% of cases) and subluxation/dislocation of the peroneal tendons (47% of cases). Structural abnormalities of the peroneal tendons were associated with a higher MDS including chronic tenosynovitis (eight cases), chronic partial tendon rupture (eight cases), complete peroneus brevis tendon rupture (two cases) and scarring indicating stenosing tenosynovitis (14 cases). A similar spectrum of appearances affecting the medial tendons of the hindfoot was identified in eight cases. Direct CT measurements of the degree of comminution did not correlate well with the patients' MDS. In the patient with persistent symptoms, CT is of value in the later assessment of long-term complications by revealing abnormalities of the subtalar joints and adjacent tendons.

Proton-linked L-fucose transport in Escherichia coli.

1. Addition of L-fucose to energy-depleted anaerobic suspensions of Escherichia coli elicited an uncoupler-sensitive alkaline pH change diagnostic of L-fucose/H+ symport activity. 2. L-Galactose or D-arabinose were also substrates, but not inducers, for the L-fucose/H+ symporter. 3. L-Fucose transport into subcellular vesicles was dependent upon respiration, displayed a pH optimum of about 5.5, and was inhibited by protonophores and ionophores. 4. These results showed that L-fucose transport into E. coli was energized by the transmembrane electrochemical gradient of protons. 5. Neither steady state kinetic measurements nor assays of L-fucose binding to periplasmic proteins revealed the existence of a second L-fucose transport system.