How is income generated by outpatient parenteral antibiotic treatment (OPAT) in the UK? Analysis of payment tariffs for cellulitis.

OBJECTIVES: We determined the available mechanisms to generate income from outpatient parenteral antimicrobial therapy (OPAT) in the UK and calculated the revenue generated from treatment of an episode of cellulitis. METHODS: Revenue was calculated for patients receiving treatment for cellulitis as an inpatient and for patients receiving OPAT by a series of different payment pathways. Selected established OPAT services in Northern Ireland, Scotland and Wales, where Payment-by-Results (PbR) does not operate, were contacted to determine individual national funding arrangements. RESULTS: In England, a traditional inpatient episode for uncomplicated cellulitis requiring 7 days of treatment generated £1361 of revenue, while OPAT generated revenue ranging from £773 to £2084 for the same length of treatment depending on the payment pathway used. Treatment using OPAT to avoid admission entirely generated £2084, inpatient admission followed by transfer to a virtual OPAT ward at day 2 generated £1361 and inpatient admission followed by discharge from hospital to OPAT at day 2 generated £773. In Northern Ireland, Scotland and Wales block contracts were used and no income was calculable for an individual episode of cellulitis. CONCLUSIONS: No single funding mechanism supports OPAT across the UK. In England, revenue generated by OPAT providers from treatment of cellulitis varied with the OPAT payment pathway used, but equalled or exceeded the income generated from equivalent inpatient care. Cost savings for OPAT and reuse of released inpatient beds will increase revenue further. A single OPAT tariff is proposed.

Level of ex vivo interleukin 6 expression in human peripheral fat compared with other tissues.

OBJECTIVES: Adipose tissue is able to secrete a variety of active mediators into the circulation. One of these is Interleukin 6 (IL6). IL6 may play a causal role in the development of atherosclerosis. It has therefore been suggested that IL6 may form part of the link between obesity and vascular disease. The aim of this study was to quantify the relative IL6 expression in adipose tissue compared to other tissues. METHODS: Tissue (vein, fat, muscle, blood) was collected from 32 patients undergoing varicose vein surgery. RNA was extracted and mRNA measured using RT-PCR relative quantification. The mean relative IL6 mRNA levels were compared between tissues using the Mann Whitney U test and the independent t-test. Tissue levels were compared for individuals using the Wilcoxon signed rank test. RESULTS: Mean relative IL6 mRNA levels (mean+/-SEM) were significantly greater in adipose tissue 44.8+/-16.1 than in other tissues (leukocytes 1.1+/-0.3, vein 2.0+/-0.8, muscle 0.06+/-0.03: p<0.001). mRNA expression levels were also significantly higher in fat than in all other tissue types in individuals (p<0.001). CONCLUSIONS: IL6 mRNA expression is significantly higher in adipose than in many other tissues known to express IL6.

Skeletal muscle extra-aortic counterpulsation in dogs with dilated cardiomyopathy.

Skeletal muscle extra-aortic counterpulsation was performed in seven dogs with dilated cardiomyopathy. A left latissimus dorsi dynamic descending thoracic aortomyoplasty was used as the autologous counterpulsator. Pulse train stimulation in diastole was used to initiate contraction and fibre type transformation. Two of the dogs died within 48 hours of surgery. The device was successfully activated in the five remaining dogs, but in one individual it failed within 48 hours of activation. Serial echocardiographic examinations of dogs in which the device functioned successfully (n = 4) showed trends towards the decrease in the left ventricular systolic internal dimension, left ventricular diastolic internal dimension, E-point to septal separation and left atrial diameter in systole seven to 14 days following the procedure, although these changes failed to persist in the long-term. The results suggest that skeletal muscle for cardiac assistances such as extra-aortic muscle counterpulsation, might be a therapeutic option for dogs with cardiac failure due to dilated cardiomyopathy.

Differential protection of primary rat cardiocytes by transfection of specific heat stress proteins.

The aim of this study was to examine the individual contribution of specific heat stress proteins in primary rat cardiocytes to any protection observed following lethal heat stress or simulated lethal ischaemia. cDNAs for the inducible heat stress protein 70, for heat stress proteins 90 or 60, or a control plasmid were contransfected with a detectable marker, alkaline phosphatase, into cardiocytes. Survival assays were performed after the lethal stress. Transfection of the inducible heat stress protein 70 was found to increase survival following a lethal heat stress by 2.45-fold (P < 0.01) and against lethal ischaemia by 2.71-fold (P < 0.01). Transfection of heat stress protein 90 improved survival against heat by 2.55-fold (P < 0.05) but failed to have any effect on survival against lethal ischaemia. Transfection of heat stress protein 60 offered no protection against either stress.

Pharmacological preconditioning of primary rat cardiac myocytes by FK506.

Pre-treatment with the immunosuppressant FK506 is shown to protect primary cardiocytes against a subsequent severe thermal or ischaemic stress. This effect is not observed with the related compounds cyclosporin A or rapamycin. It does not involve induction of the FK506 binding, heat inducible protein hsp56 or of the other heat shock proteins. In addition over-expression of hsp56 does not protect cardiac cells from severe stress in contrast to our previous results with hsp70 and hsp90. These results suggest the FK506 is acting via a novel mechanism to protect cardiac cells against cellular ischaemia which may not be related to its immunosuppressant action.

Gene delivery to the heart in vivo and to cardiac myocytes and vascular smooth muscle cells in vitro using herpes virus vectors.

Herpes simplex virus 1 (HSV1), while usually thought of as neurotrophic, can also efficiently infect a wide variety of non-neuronal cell types and so might be developed as a vector for gene delivery to non-neuronal as well as neuronal cells. Here we have tested three different disabled HSV vectors for their ability to deliver a lacZ gene to primary cardiac myocytes and vascular smooth muscle cells in vitro, and used the most efficient virus to transfect the rat heart in vivo. We also assessed the degree of cytopathic effect of the various viruses on the cardiac myocytes in vitro by testing the effects on the frequency of beating in synchronously beating myocyte cultures. While an HSV mutant in which the essential immediate-early gene IE2 had been deleted gave high efficiency gene transfer to the cardiac myocytes in vitro and the rat heart in vivo, viruses in which ICP34.5 or ICP34.5 and VMW65 were inactive (and which were also unable to replicate in these cells) gave a much lower efficiency of gene transfer, mirroring the degree of cytopathic effect observed in the beating myocyte cultures. Gene transfer to the vascular smooth muscle cells was considerably less efficient than to the myocytes in all cases. These results indicate that while HSV may be inappropriate for highly efficient gene transfer to the arterial wall, efficient gene transfer can be achieved in the myocardium, and thus that HSV vectors may be suitable for the alteration of cardiac cell physiology in vivo.

Over-expression of heat shock protein 70 protects neuronal cells against both thermal and ischaemic stress but with different efficiencies.

Primary cultures of dorsal root ganglia (DRG) sensory neurons can be protected against subsequent severe thermal or ischaemic stress by prior exposure to a mild thermal or ischaemic insult. The degree of protection correlates with the amount of 70 kDa heat shock protein (hsp70) induced by the mild stress. We show directly that over-expression of hsp70 alone is sufficient to protect DRG neurons against thermal or ischaemic stress with a given level of hsp70 over-expression providing greater protection against thermal stress. In contrast over-expression of the 90 kDa heat shock protein (hsp90) has little or no protective effect against either stress. These results are discussed in terms of the role of individual hsps in protecting neuronal cells against different stresses.

Specific induction of the 70-kD heat stress proteins by the tyrosine kinase inhibitor herbimycin-A protects rat neonatal cardiomyocytes. A new pharmacological route to stress protein expression?

Heat shock protein (hsp) induction by stressful stimuli such as heat and ischemia is known to protect cardiac cells from severe stress. The ability to induce hsp's in the heart directly by "nonstressful" means would potentially have important clinical implications. In noncardiac cells, the tyrosine kinase inhibitor herbimycin-A has been shown to induce the 72-kD hsp. We therefore examined whether herbimycin-A and another tyrosine kinase inhibitor, genistein, could induce 70-kD hsp's in primary cultures of rat neonatal cardiomyocytes, and whether these treatments protect against severe stress. Primary cardiomyocytes were incubated with herbimycin-A or genistein. hsp induction was measured 16-20 h later by Western blotting. Cell survival after subsequent lethal heat stress or simulated ischemia was assessed using trypan blue exclusion and released lactate dehydrogenase activity. Our results indicate that, in cardiac cells, herbimycin-A induces 70-kD hsp's but not hsp90, -60, -25, or glucose-regulated protein 78, whereas genistein has no effect on hsp's. Moreover, hsp induction correlated with the ability of herbimycin-A to protect cells against severe stress, whereas genistein has no protective effects. This suggests that herbimycin-A may induce 70-kD hsp's via a tyrosine kinase-independent mechanism. These results indicate the possibility of a pharmacological approach to HSP70 induction and cardiac protection, which may ultimately be of clinical relevance.

The ability of heat stress and metabolic preconditioning to protect primary rat cardiac myocytes.

Primary rat cardiocytes were subjected to either thermal "preconditioning" for 30 min at 43 degrees C or 20 min metabolic "preconditioning" (10 mM deoxyglucose, 20 mM lactate, pH 6.5). Eighteen hours later cells were analysed either for hsp 70i expression or subjected to a subsequent lethal heat stress or simulated ischaemia (10 mM deoxyglucose, 20 mM lactate, 0.75 mM sodium dithionite, 12 mM potassium chloride, pH 6.5) for 2 hours and assessed for survival by trypan blue exclusion. Hsp 70i was induced over 100 fold by thermal "preconditioning" and 30 fold by metabolic "preconditioning" (p < 0.001, p < 0.05), hsp 90 was induced 2.71 fold and 2.24 fold (p < 0.001, p < 0.001) by thermal and metabolic "preconditioning" respectively, while hsp 60 was no induced by either treatment. Preconditioned cultures had improved survival against subsequent lethal heat stress or simulated ischaemia: Thermal "preconditioning" reduced death from 69.22% to 52.46% upon subsequent "lethal" heat stress and from 49.13% to 36.66% upon subsequent "lethal" simulated ischaemia. Metabolic "preconditioning" reduced cell death from 51.29% to 33.8% against subsequent "lethal" heat stress, and from 69.09% to 55.61% upon subsequent "lethal" simulated ischaemia. A second marker of cell death, the release of lactate dehydrogenase activity into the culture media, was reduced to 65% and 60% of control values for thermally preconditioned cells subjected to "lethal" heat or "lethal" simulated ischaemia respectively. Metabolically "preconditioned" cells demonstrated lactate dehydrogenase activity of 59% and 51% that of control values, when subjected to "lethal" heat or "lethal" simulated "ischaemia" respectively.

The degree of protection provided to neuronal cells by a pre-conditioning stress correlates with the amount of heat shock protein 70 it induces and not with the similarity of the subsequent stress.

A mild thermal stress protects primary cultures of dorsal root ganglion (DRG) neurons against a subsequent lethal heat stress as well as to a lesser extent against a subsequent lethal ischaemia. In contrast, a mild ischaemic stress protects DRG neurons only against a subsequent severe thermal stress and not against severe ischaemia. A greater induction of heat shock protein (hsp) synthesis was observed in these cells following mild temperature stress compared to mild ischaemia. This suggests that the protective effect observed is dependent on hsp synthesis resulting in the observed cross-protective effect and does not involve a particular pre-stress specifically protecting against a subsequent, more severe application of the same stress. Moreover, a particular level of hsp induction produces a better protective effect against lethal heat stress than against lethal ischaemia.

Myoplasty--a surgical option for end-stage heart failure.

Congestive heart failure is a growing problem in the Western world, which modern therapeutic options are doing little to ameliorate. Dynamic cardiomyoplasty may be one option which has great potential. This article reviews the use of skeletal muscle for circulatory assist and suggests that, with further work, it should take a significant place in the treatment armamentarium.

Physiology and clinical applications of cardiopulmonary exercise testing.

Advances in the technology of gas exchange analysers have made cardiopulmonary exercise testing a relatively simple, cheap and reliable diagnostic tool. Its practice and uses include grading the severity of heart failure, evaluation of the cause of exertional dyspnoea and monitoring a patient's response to therapy. Areas of debate and future development are highlighted.

Troponin I and T protein expression in experimental cardiac hypertrophy.

We have examined four models of experimental cardiac hypertrophy and heart failure for alterations in troponin isoform expression, particularly in the re-expression of the fetal isoforms. Cardiac protein extracts from experimental and sham-operated control rats were analyzed using one dimensional gel electrophoresis, followed by Western blotting and detection with antibodies specific for troponin I and T. No alteration in protein profile was observed for these proteins between control, hypertrophied and failing heart samples. The data demonstrate that reversion to the fetal pattern of troponin expression is not a feature of experimental cardiac hypertrophy and heart failure in the rat.

Metabolic analysis of latissimus dorsi coupled to a mock circulation.

A mock circulation system has been used to examine the metabolic and hemodynamic responses of untrained and trained latissimus dorsi muscle in a normal animal model. The metabolic response of untrained latissimus dorsi to differing stimulation regimes runs parallel to its mechanical performance. The ratio of power generated to oxidative capacity (a measure of metabolic efficiency) was maintained to a greater extent in muscle trained for 5 months subjected to specific fatigue tests, falling by only 20% (as opposed to 80% observed in untrained control muscle). This approach to studying metabolic and hemodynamic performance may have relevance when skeletal muscle is used for cardiac assistance.

Electrophoretic analysis of electrically trained skeletal muscle.

Sheep latissimus dorsi muscle was electrically trained, thereby inducing fast-to-slow fibre-type transformation. Using a combination of one- and two-dimensional gel electrophoresis techniques with computer analysis, we have analysed altered expression of contractile protein isoforms at protein and mRNA level over a time course of electrical training extending to 5 months. Myosin heavy chain and regulatory myosin light chain analysis showed predominant expression of their slow isoforms (86% and 92%, respectively) after 3 months of training. At the same time point, however, tropomyosin analysis revealed that the slow isoform of the alpha-subunit accounted for 64% of the total alpha expression. Troponin T isoform switching proceeded more slowly over the same time course than tropomyosin and the thick filament proteins studied. Troponin T analysis revealed 5 fast and 2 slow isoforms in the sheep, of which the second slow isoform only became clearly visible after 5 months' training. At this time point the two slow isoforms were more predominant than their fast counterparts. This suggests that a wide heterogeneity of fast and slow isoform combinations are possible in the thin filament of skeletal muscle.

Aortic counterpulsation for up to 28 days with autologous latissimus dorsi in sheep.

This article reports the development and assessment of an entirely autologous extraaortic counterpulsation system using skeletal muscle (latissimus dorsi). The technique has been performed and assessed in 16 sheep to quantify the effectiveness of counterpulsation over periods up to 28 days and to optimize the stimulation regimens for muscle contraction and fiber-type transformation. Hemodynamic changes have been quantified by calculation of the endocardial viability ratio. This has shown an increase of between 12% and 89% for 28 days. The wide variety of increase observed has been related to the development of an optimum flap configuration. The technique of surface impedance monitoring of flap blood flow has allowed the start of electrical stimulation after 48 hours with the introduction of hemodynamic benefit (1:4 mode) during the process of fiber-type transformation (in situ training). Extraaortic counterpulsation with autologous latissimus dorsi has been shown to be effective and safe for as long as 28 days. It has not been associated with any thromboembolic or infective complications, which we attribute to the exclusion of any foreign material in the design.

Developmental expression of troponin I isoforms in fetal human heart.

We have used antibodies specific for troponin I proteins to examine human cardiac development and have detected a transiently expressed developmental isoform. This isoform is distinct from adult cardiac troponin I (TnIc) but is indistinguishable, on the basis of electrophoretic mobility and antibody reactivity, from the isoform found in slow skeletal muscle (TnIs). Furthermore, we show that mRNA for TnIs is present in fetal, but not adult, heart. Analysis of a developmental series of fetal samples indicates that there is a transition in expression from TnIs to TnIc which occurs between 20 weeks fetal and 9 months postnatal development.

Development of mock circulation models for the assessment of counterpulsation systems.

STUDY OBJECTIVE: This study entailed the development of mock circulation models to assess and compare the haemodynamic efficacy of extra-aortic counterpulsation (using trained skeletal muscle wrapped around the proximal descending aorta) and conventional intra-aortic balloon counterpulsation. DESIGN AND EXPERIMENTAL MATERIALS: Hydraulic Windkessel type lumped parameter models were used either in conjunction with native skeletal muscle or as a dynamic simulation of counterpulsation. The haemodynamic performance of the wrapped latissimus dorsi muscle of the normal sheep was assessed using an artificial load to simulate the pressurised proximal descending aorta. Mock circulation models of counterpulsation comprised Windkessel compliance chambers, laminar flow resistors, a blood analogue, a prosthetic blood pump, and a purpose made hydraulic counterpulsator. MEASUREMENTS AND MAIN RESULTS: An electrically stimulated muscle wrap, 5 cm in length, previously trained for 2 weeks at 3 V and 35 Hz, was assessed for haemodynamic performance in a mock circulation: volume of fluid displaced = 14.1(SD 1.8) ml; pressure increase from 100 mm Hg = 14.9(2.1) mm Hg; external work per contraction cycle = 180(70)mJ; external mean power = 800(100) mW. In a simulation of intra-aortic balloon counterpulsation, haemodynamic benefit (ie, an increase in proximal flow rate and endocardial viability ratio and a reduction in left ventricular stroke power) was assessed with respect to defined parameters. CONCLUSIONS: This paper demonstrates the potential of the mock circulation models both for the investigation of muscle wrap performance and for the comparison of extra-aortic muscle with intra-aortic balloon counterpulsation.

Development of an opiate-based anaesthetic technique for use in dogs with cardiomyopathy.

An opiate-based anaesthetic technique has been developed for use in dogs with end-stage heart failure due to dilated cardiomyopathy. It has been used in dogs undergoing translocation of the left latissimus dorsi around the descending thoracic aorta to create an autologous counterpulsation system. Anaesthesia was induced with barbiturate (10 mg/kg thiopentone) and fentanyl (500 micrograms) and maintained by an infusion of fentanyl (0.5 micrograms/kg/minute) [corrected] in addition to halothane (0.1 to 0.5 per cent) and nitrous oxide (20 to 60 per cent). This technique provided safe anaesthesia for major intrathoracic surgery.

Electrophoretic and computer analysis of skeletal muscle used for cardiac assistance.

Skeletal muscle has an inherent plasticity which allows it to undergo fibre type transformation when induced by a specific stimulus. Electrical stimulation has been used here to induce transformation of a predominantly fast type skeletal muscle towards a slow, more fatigue-resistant phenotype, which is more suitable for use in long-term cardiac assistance. Muscle samples from animals electrically stimulated for periods up to 6 months have been analysed by electrophoresis for myosin heavy chain (MHC) and myosin light chain (MLC) fast and slow isoforms. Densitometry and computer analysis have been used to determine the pattern of transformation of the different myosin subunits over this time period. MHC and MLC 2 fast to slow isoform switching preceded that of the alkali light chains (MLC1 and MLC3). After 3 months of stimulation the MHC slow isoform was found to have doubled in concentration relative to the unstimulated control muscle and by 4 months accounted for almost 50% of the total MHC content. The slow isoform accounted for 75% of the MLC2 after 4 months of stimulation. The protein products of mRNA isolated from stimulated muscle samples, translated in vitro and separated by electrophoresis, showed that transformation at the mRNA level preceded that at the protein level. By 2-4 weeks of stimulation MLC2 slow isoform mRNA represented over 60% of the total MLC2 mRNA population. An understanding of the molecular structure of muscle during transformation provides insight into its haemodynamic performance in cardiac assistance.