The structure of foot-and-mouth disease virus.

Structural studies of foot-and-mouth disease virus (FMDV) have largely focused on the mature viral particle, providing atomic resolution images of the spherical protein capsid for a number of sero- and sub-types, structures of the highly immunogenic surface loop, Fab and GAG receptor complexes. Additionally, structures are available for a few non-structural proteins. The chapter reviews our current structural knowledge and its impact on our understanding of the virus life cycle proceeding from the mature virus through immune evasion/inactivation, cell-receptor binding and replication and alludes to future structural targets.

Synthesis and secretion of a functional antibody in a vaccinia virus expression system.

A humanized rat monoclonal antibody (Campath 1H) has been expressed in HeLa cells using recombinant vaccinia viruses. Heavy and light chain recombinant viruses were constructed separately and when grown independently produced proteins of the expected molecular weights. Expressed heavy chain was entirely intracellular but light chain was mainly excreted and processed. When cells were infected at high multiplicity with both heavy and light chain recombinants a proportion of the heavy chain was then found in the extracellular medium. This secreted heavy chain was shown to be associated with light chain as judged by co-electrophoresis in non-reducing SDS polyacrylamide gels and by co-purification on protein-A sepharose. The secreted heavy and light chain complexes were functionally active as an antibody, with activity comparable to authentic Campath 1H antibody as assessed by ELISA, T-cell binding and antigen binding assays. Production of antibody in this system was achieved in the absence of serum, which is an important consideration in the production of monoclonal antibodies (MAbs). The amount of antibody produced was 0.2-0.4 micrograms/10(6) cells without optimization of expression levels. The wide host cell range of vaccinia virus together with the recently developed methods for increasing expression levels make this an attractive candidate as a flexible general vehicle for producing MAbs.

The nucleotide sequence of cDNA coding for the structural proteins of foot-and-mouth disease virus.

The complete nucleotide sequence of cDNA coding for the structural capsid polypeptides of foot-and-mouth disease virus (FMDV) (strain A(10)61) has been determined. Portions of the flanking sequence coding for the nonstructural proteins p20a and p52 are also provided. The three larger structural polypeptides VP1, VP2 and VP3 have unmodified Mrs of 23248, 24649 and 24213, respectively. The size of the smaller polypeptide, VP4, can only be estimated at 7360 because the 5'-limit of its coding region is not yet known with certainty. The sequence data for VP1 (the major immunising antigen) and the amino-terminal quarter of p52 are compared with the data of Kurz et al. (Nucl. Acids Res. 9 (1981) 1919-1931) for a different serotype (O1K). This shows that variation is much greater in the region coding for VP1 than in that coding for p52. This is reflected in the level of amino acid sequence variation predicted for the two proteins. Analysis of relative codon usage reveals a strong bias in favour of C and G over U and A in the third base position. The dinucleotide frequencies show a bias against A-U and U-A, and for A-C and C-A.

The sequence of foot-and-mouth disease virus RNA to the 5' side of the poly(C) tract.

The nucleotide sequence of foot-and-mouth disease virus (FMDV) RNA to the 5' side of the poly(C) tract (S fragment) has been determined for representatives of the A and O serotypes of the virus. The two S fragments differ in length by five nucleotides (nt), with 367 nt for O1 compared with 362 nt for A10, due to a number of insertions/deletions. However, the two sequences show 86% homology. There are no conserved open reading frames (ORFs). Secondary structure predictions reveal a high degree of potential base-pairing, such that the entire S fragment sequence can be folded into a hairpin structure.

Synthetic peptides mimic subtype specificity of foot-and-mouth disease virus.

The major immunogen of foot-and-mouth disease virus (FMDV) is located between amino acids 141-160 of the capsid protein VP1. Synthetic peptides corresponding to the major immunogenic region give good neutralising antibody responses and protection in guinea pigs. To define more precisely the immunogenic site of the virus, we have examined serological differences between subtypes of the A serotype using synthetic peptides covering the 141-160 region. We show that these synthetic peptides carry determinants which mimic the subtype specificity of the virus. The correlation between these results and predictive structural models, based on the amino acid sequence, is discussed.

The management of arrhythmias following an acute myocardial infarction.

Arrhythmias are extremely common early after AMI. An arrhythmia is defined by exclusion, either because the sequence of myocardial depolarisation is other than normal or because certain arbitrary limits are exceeded. It follows that the term "arrhythmia" encompasses a complex heterogenous group. Although arrhythmias are defined in electrical terms they are only important because of their immediate, delayed or potential haemodynamic consequences. These occur because of changes in heart rate, loss of atrial transport function, increased myocardial oxygen consumption, decreased myocardial blood flow or loss os synchronicity of ventricular contraction. The sensible and effective management of arrhythmias following acute myocardial infarction requires an appraisal of the haemodynamic consequences, if any, which follow the initiation of the arrythmia. The indications for treating an arrhythmia must be the immediate, delayed or potential haemodynamic loss rather than the mere presence of a rhythm which falls outside the limits of normal. This distinction is perhaps most clearly seen in the case of atrio-ventricular conduction disturbances.

Study of right ventricular function in ischaemic heart disease using radionuclide angiocardiography.

A technique for the estimation of LVEF from first passage radionuclide angiocardiography was adapted to provide estimates of RVEF. In 17 subjects with no history of cardiovascular disease mean LVEF was 0.71 +/- 0.08 and mean RVEF 0.65 +/- 0.08. Mean values for 15 subjects with coronary artery disease but no previous history of myocardial infarction were 0.66 +/- 0.10 for LVEF and 0.65 +/- 0.08 for RVEF. Depressed ejection fractions were found after acute myocardial infarction. LVEF was lower after anterior (0.43 +/- 0.06) than inferior (0.51 +/- 0.10) infarction. RVEF was normal in the majority of subjects with anterior infarction (0.58 +/- 0.10) but was depressed after inferior infarction (0.50 +/- 0.05). Similar, although less marked, results were found in a group of subjects with old myocardial infarction.

How can peptide vaccines work?

Peptide antigens frequently induce antibodies which recognise the denatured form of a protein from which their sequences are derived. However, the ability to induce antibodies which crossreact with the native, fully folded form of the protein is less commonly observed. Although there is a growing number of examples in which this is the case, the ability to predict peptides having this property is extremely limited. Given the large surface areas involved in antibody/antigen interaction it is surprising that peptides could ever induce antibodies which would recognise the native protein well enough to have biological activity, such as the neutralization of infectivity. A mechanism is proposed to explain such observations which is compatible with many of the properties of antipeptide antibodies.

A multi-centre randomised controlled trial of minimally invasive direct coronary bypass grafting versus percutaneous transluminal coronary angioplasty with stenting for proximal stenosis of the left anterior descending coronary artery.

OBJECTIVES: To compare the clinical- and cost-effectiveness of minimally invasive direct coronary artery bypass grafting (MIDCAB) and percutaneous transluminal coronary angioplasty (PTCA) with or without stenting in patients with single-vessel disease of the left anterior descending coronary artery (LAD). DESIGN: Multi-centre randomised trial without blinding. The computer-generated sequence of randomised assignments was stratified by centre, allocated participants in blocks and was concealed using a centralised telephone facility. SETTING: Four tertiary cardiothoracic surgery centres in England. PARTICIPANTS: Patients with ischaemic heart disease with at least 50% proximal stenosis of the LAD, suitable for either PTCA or MIDCAB, and with no significant disease in another vessel. INTERVENTIONS: Patients randomised to PTCA had local anaesthetic and underwent PTCA according to the method preferred by the operator carrying out the procedure. Patients randomised to MIDCAB had general anaesthetic. The chest was opened through an 8-10-cm left anterior thoracotomy. The ribs were retracted and the left internal thoracic artery (LITA) harvested. The pericardium was opened in the line of the LAD to confirm the feasibility of operation. The distal LITA was anastomosed end-to-side to an arteriotomy in the LAD. All operators were experienced in carrying out MIDCAB. MAIN OUTCOME MEASURES: The primary outcome measure was survival free from cardiac-related events. Relevant events were death, myocardial infarction, repeat coronary revascularisation and recurrence of symptomatic angina or clinical signs of ischaemia during an exercise tolerance test at annual follow-up. Secondary outcome measures were complications, functional outcome, disease-specific and generic quality of life, health and social services resource use and their costs. RESULTS: A total of 12,828 consecutive patients undergoing an angiogram were logged at participating centres from November 1999 to December 2001. Of the 1091 patients with proximal stenosis of the LAD, 127 were eligible and consented to take part; 100 were randomised and the remaining 27 consented to follow-up. All randomised participants were included in an intention-to-treat analysis of survival free from cardiac-related events, which found a non-significant benefit from MIDCAB. Cumulative hazard rates at 12 months were estimated to be 7.1 and 9.2% for MIDCAB and PTCA, respectively. There were no important differences between MIDCAB and PTCA with respect to angina symptoms or disease-specific or generic quality of life. The total NHS procedure costs were 1648 British pounds and 946 British pounds for MIDCAB and PTCA, respectively. The costs of resources used during 1 year of follow-up were 1033 British pounds and 843 British pounds, respectively. CONCLUSIONS: The study found no evidence that MIDCAB was more effective than PTCA. The procedure costs of MIDCAB were observed to be considerably higher than those of PTCA. Given these findings, it is unlikely that MIDCAB represents a cost-effective use of resources in the reference population. Recent advances in cardiac surgery mean that surgeons now tend to carry out off-pump bypass grafting via a sternotomy instead of MIDCAB. At the same time, cardiologists are treating more patients with multi-vessel disease by PTCA. Future primary research should focus on this comparison. Other small trials of PTCA versus MIDCAB have now finished and a more conclusive answer to the original objective could be provided by a systematic review.

Detection of coronary artery bypass graft patency as assessed by magnetic resonance imaging.

In a study of 22 patients with 60 coronary artery bypass grafts, magnetic resonance imaging (MRI) correctly assessed graft patency or occlusion in 90% of cases when compared with selective coronary graft angiography and computed tomography. It is concluded that MRI can detect a normally functioning coronary artery bypass graft and could be used as a non-invasive technique to assess graft patency in patients presenting with post-operative angina.

Magnetic resonance (MR) cine imaging of the human heart.

A novel approach has been developed for MR cine imaging of the human heart by a modified ECG-gated 2DFT method. A pulse sequence has been devised to minimise the effects of saturation which can be anticipated in sequences that require rapid pulsing. Five frames are produced at the same anatomical level at predetermined intervals during the cardiac cycle. The total time taken to achieve this data is 8 minutes. Additional frames can be interleaved by repeating the sequence with an ECG-gated delay. The anatomical sections, which can be in any orthogonal plane, are then displayed as a cine loop. Cine display in the coronal plane has been used to examine 10 volunteers and 12 patients. In addition to the morphological feature displayed in single slice ECG-gated imaging, areas of dyskinesia can be detected and subjective estimates have been made of left ventricular function.

Association of conventional and exertional coronary heart disease risk factors in 5,000 apparently healthy men.

BACKGROUND AND HYPOTHESIS: The aim of this study was to define the prevalence of previously undetected coronary heart disease among asymptomatic males, aged 30-65 years, by means of resting and exercise electrocardiography in conjunction with an analysis of conventional and exertional coronary risk factors. METHODS: Between January 1985 and December 1989 we examined 5,000 clinically asymptomatic subjects. A detailed case history was obtained for each individual, followed by a complete physical examination, comprehensive blood (including lipid) profile, lung function tests, chest x-ray, a resting 12-lead electrocardiogram (ECG), and a maximal treadmill exercise ECG. Whenever possible, on-line computerized respiratory analysis (Beckman Metabolic Measurement Cart) was carried out during the exercise tests. Conventional and exertional coronary heart disease risk factors were also recorded. RESULTS: A total of 162 persons (3.2%) showed abnormal S-T segment responses during the exercise or recovery period. Of these, 92 subjects underwent further investigations: coronary angiography (79), 201thallium scanning (13), 201thallium scanning followed by coronary angiography (7). Of the 86 patients who proceeded to coronary angiography, 19 (22%) had either normal coronary artery anatomy or only insignificant disease. Among the 67 (78%) of patients with significant angiographically demonstrable disease, 26 received coronary artery bypass grafting, 7 underwent coronary angioplasty, and the remainder continued on medical management. CONCLUSIONS: These results are discussed in relation to a variety of conventional and exertional coronary risk factors.

Encephalomyocarditis virus antibodies in sera from apparently normal pigs.

Antibodies which neutralise and precipitate encephalomyocarditis virus habe been found in the serum of more than 28 per cent of normal pigs in Britain. Neutralising activity was found in association with several size classes of antibody.