A new method for the analysis of access period experiments, illustrated with whitefly-borne cassava mosaic begomovirus

Reports of low transmission efficiency, of a cassava mosaic begomovirus (CMB) in Bemisia tabaci whitefly, diminished the perceived importance of whitefly in CMB epidemics. Studies indicating synergies between B. tabaci and CMB prompt a reconsideration of this assessment. In this paper, we analysed the retention period and infectiousness of CMB-carrying B. tabaci as well as B. tabaci susceptibility to CMB. We assessed the role of low laboratory insect survival in historic reports of a 9d virus retention period. To do this, we introduced Bayesian analyses to an important class of experiment in plant pathology. We were unable to reject a null hypothesis of life-long CMB retention when we accounted for low insect survival. Our analysis confirmed low insect survival, with insects surviving on average for around three days of transfers from the original infected plant to subsequent test plants. Use of the new analysis to account for insect death may lead to re-calibration of retention periods for other important insect-borne plant pathogens. In addition, we showed that B. tabaci susceptibility to CMB is substantially higher than previously thought. We also introduced a technique for high resolution analysis of retention period, showing that B. tabaci infectiousness with CMB was increasing over the first five days of infection.

Incidence of cerebrovascular accident following head and neck free tissue transfer surgery

The aim of this study was to determine the incidence of postoperative cerebrovascular accident (CVA) following head and neck free tissue transfer and to identify predictive risk factors. A retrospective audit was performed of patients who underwent head and neck reconstructive surgery at Queen Elizabeth University Hospital between 2009 and 2020. The patient records were analysed to identify those who developed CVA within 30 days after surgery. A total of 1109 patients underwent head and neck free tissue transfer surgery, including 1048 neck dissection procedures. Of these, 78.6% had one or more identified risk factors for perioperative stroke. Five patients (0.45%) developed postoperative CVA. The results showed that CVA correlated to patients with hypercholesterolemia (P = 0.007). This study demonstrates the safety of free tissue transfer. Despite underlying co-morbidities and risk factors, the incidence of CVA is low following surgery and manipulation of the major vasculature of the neck.

84 A PROSPECTIVE AUDIT OF THE MANAGEMENT OF POSTOPERATIVE ANAEMIA IN PATIENTS AFTER OPERATIVE MANAGEMENT OF NECK OF FEMUR FRACTURES

Background

There is limited evidence available to guide the diagnosis and management of anaemia and iron deficiency in post operative patients. Numerous guidelines from professional associations exist for the management of pre-operative anaemia. We identified an international consensus statement that provided guidance on patient care with respect to postoperative anaemia and iron deficiency. Our aim was to determine if our practice was consistent with the best practice recommendations of this document.

Methods

We conducted a prospective audit on a convenience sample of patients over the age of 60 with neck of femur fractures who underwent operative management between January and April 2022. We collected data on pre and post operative haematological indices including haemoglobin, serum iron, ferritin and transferrin saturation as well as data on patients who received IV iron and red cell transfusions.

Results

We included 50 patients with neck of femur fractures who underwent hip replacement. All patients had post-op haemoglobin levels performed. Fifteen (30%) patients fulfilled the criteria for diagnosis of postoperative iron deficiency. Only 4/15 of these patients received IV iron postoperatively. Four patients who did not fulfil criteria for post-op iron deficiency received IV iron. Two patients had a post-op haemoglobin between 7-8g/dL and appropriately received red cell transfusions. Four patients received red cell transfusions despite having post-op haemoglobin levels >8g/dL.

Conclusion

Our findings indicated approximately 1/3 of patients fulfilled criteria for post operative iron deficiency while only a small proportion were treated for this. More data is required to establish the impact of post-op anaemia management strategies on functional recovery and quality of life as well as laboratory and interventional endpoints. A local protocol for the management of post operative iron deficiency with and without anaemia will be developed.

301 BENEFITS OF ENVIRONMENTAL MUSIC THERAPY IN AN ACUTE HOSPITAL

Background

Environmental Music Therapy (EMT) uses live music played by a music therapist to enhance the surrounding environment and is increasingly used in clinical settings. Studies show that EMT may reduce anxiety, enhance wellbeing, promote better communication between patients and staff, and reduce patient perception of waiting times in hospital. We aimed to explore the benefit of EMT for older adults in a geriatric outpatient setting and on rehabilitation wards.

Methods

Harp music was played by a music therapist in the vicinity of ambulatory clinics and on rehabilitation wards for 4 hours per week (over a 2-day period) for 20 weeks. Music exposure on any given day was to an estimated 50 outpatients, as well as 50 people passing the vicinity or to about 30 patients on the rehabilitation ward. Music was selected and played in a dynamic process, responding to verbal and non-verbal reactions of patients, family, and staff. Voluntary responses were recorded and collated.

Results

There were 36 recorded responses and all reflected positively on EMT. Patients cited that the music created a welcoming space and stimulated interaction and conversation. Several patients waiting for their clinic appointment noted that it distracted from fearful expectation and was a source of comfort. Some commented that they felt more relaxed and that it reduced stress. On rehabilitation wards, patients found familiar music to be calming with nurses citing that it stimulated social interaction between patients, family and staff. Responses to EMT gave insights that resulted in patient referrals for music therapy.

Conclusion

Environmental music played by a music therapist was found to modify patient hospital experiences. In particular, it appeared to reduce self-perceived stress and stimulate positive social interaction and conversation. This supports the use of EMT to advance the integration of the arts for wellbeing in an acute hospital.

The role of pathogen-mediated insect superabundance in the East African emergence of a plant virus

One of the major crops for food security is cassava. Superabundant Bemisia tabaci whitefly, comprising unusually high landscape populations of the insect, have been implicated in cassava virus emergence. Studies have been unable to select from several hypotheses, however, as to the dynamic drivers of superabundant whitefly associated with the emergence in East Africa of severe cassava mosaic disease. One possibility is that pathogenic modification of infected plants can itself increase the growth of insect vector colonies on infected plants.Through the modelling of population processes at the landscape scale we introduce a framework for analysing patterns in the association of disease and insect waves.Our analyses demonstrate the role of pathogen-mediated insect superabundance in a plant disease invasion. Synthesis. An elevated abundance of insects at the landscape scale is frequently implicated in invasions of the plant pathogens that they carry. We advance ecological understanding of plant disease invasions by showing how landscape data can be used to investigate the causes of insect vector superabundance.

COVID-19 hospitalization rates rise exponentially with age, inversely proportional to thymic T-cell production

Here, we report that COVID-19 hospitalization rates follow an exponential relationship with age, doubling for every 16 years of age or equivalently increasing by 4.5% per year of life (R2 = 0.98). This mirrors the well-studied exponential decline of both thymus volume and T-cell production, which halve every 16 years. COVID-19 can therefore be added to the list of other diseases with this property, including those caused by methicillin-resistant Staphylococcus aureus, MERS-CoV, West Nile virus, Streptococcus pneumoniae and certain cancers, such as chronic myeloid leukaemia and brain cancers. In addition, the incidence of severe disease and mortality due to COVID-19 are both higher in men, consistent with the degree to which thymic involution (and the decrease in T-cell production with age) is more severe in men compared to women. Since these properties are shared with some non-contagious diseases, we hypothesized that the age dependence does not come from social-mixing patterns, i.e. that the probability of hospitalization given infection rises exponentially, doubling every 16 years. A Bayesian analysis of daily hospitalizations, incorporating contact matrices, found that this relationship holds for every age group except for the under 20s. While older adults have fewer contacts than young adults, our analysis suggests that there is an approximate cancellation between the effects of fewer contacts for the elderly and higher infectiousness due to a higher probability of developing severe disease. Our model fitting suggests under 20s have 49-75% additional immune protection beyond that predicted by strong thymus function alone, consistent with increased juvenile cross-immunity from other viruses. We found no evidence for differences between age groups in susceptibility to infection or infectiousness to others (given disease state), i.e. the only important factor in the age dependence of hospitalization rates is the probability of hospitalization given infection. These findings suggest the existence of a T-cell exhaustion threshold, proportional to thymic output and that clonal expansion of peripheral T-cells does not affect disease risk. The strikingly simple inverse relationship between risk and thymic T-cell output adds to the evidence that thymic involution is an important factor in the decline of the immune system with age and may also be an important clue in understanding disease progression, not just for COVID-19 but other diseases as well.

What is pathogen-mediated insect superabundance?

When increasing abundance of insect vectors is manifest across multiple fields of a crop at the landscape scale, the phenomenon is sometimes referred to as insect superabundance. The phenomenon may reflect environmental factors (i.e. environmentally mediated insect superabundance, EMiS), including climatic change. A number of pathogens, however, are also known to modify the quality of infected plants as a resource for their insect vectors. In this paper, we term increasing vector abundance when associated with pathogen modification of plants as pathogen-mediated insect superabundance (henceforth PMiS). We investigate PMiS using a new epidemiological framework. We formalize a definition of PMiS and indicate the epidemiological mechanism by which it is most likely to arise. This study is motivated by the occurrence of a particularly destructive cassava virus epidemic that has been associated with superabundant whitefly populations in sub-Saharan Africa. Our results have implications for how PMiS can be distinguished from EMiS in field data. Above all, they represent a timely foundation for further investigations into the association between insect superabundance and plant pathogens.

Estimating epidemiological parameters from experiments in vector access to host plants, the method of matching gradients

Estimation of pathogenic life-history values, for instance the duration a pathogen is retained in an insect vector (i.e., retention period) is of particular importance for understanding plant disease epidemiology. How can we extract values for these epidemiological parameters from conventional small-scale laboratory experiments in which transmission success is measured in relation to durations of vector access to host plants? We provide a solution to this problem by deriving formulae for the empirical curves that these experiments produce, called access period response curves (i.e., transmission success vs access period). We do this by writing simple equations for the fundamental life-cycle components of insect vectors in the laboratory. We then infer values of epidemiological parameters by matching the theoretical and empirical gradients of access period response curves. Using the example of Cassava brown streak virus (CBSV), which has emerged in sub-Saharan Africa and now threatens regional food security, we illustrate the method of matching gradients. We show how applying the method to published data produces a new understanding of CBSV through the inference of retention period, acquisition period and inoculation period parameters. We found that CBSV is retained for a far shorter duration in its insect vector (Bemisia tabaci whitefly) than had previously been assumed. Our results shed light on a number of critical factors that may be responsible for the transition of CBSV from sub- to super-threshold R₀ in sub-Saharan Africa. The method is applicable to plant pathogens in general, to supply epidemiological parameter estimates that are crucial for practical management of epidemics and prediction of pandemic risk.

Cassava brown streak virus (CBSV), which was confined to coastal East Africa and the shores of Lake Malawi, has rapidly expanded its geographic range and now threatens regional food security. A recent laboratory experiment, in which vector access to plants infected with CBSV is varied, has provided plausible ranges for epidemiological parameters such as pathogen retention period (i.e., the duration that the pathogen is retained by the vector). In this work we introduce a new computational and mathematical framework for estimating epidemiological parameter values, instead of plausible ranges, from experiments in vector access to host plants. Since long distance carriage of insect vectors occurs within atmospheric air flows, the duration that the vector retains the pathogen (i.e., retention period) indirectly limits the scale of epidemics. Using our methods, we found that CBSV is retained for a far shorter duration than had previously been assumed. Our methods can be applied to the many experiments in vector access to host plants that have been conducted for numerous arthropod-transmitted plant pathogens across a range of genera. The ensuing epidemiological parameter estimates can be used in landscape computer simulations to predict epidemic risk and the prospects for control.

Cucumber mosaic virus 2b proteins inhibit virus-induced aphid resistance in tobacco

Cucumber mosaic virus (CMV), which is vectored by aphids, has a tripartite RNA genome encoding five proteins. In tobacco (Nicotiana tabacum), a subgroup IA CMV strain, Fny-CMV, increases plant susceptibility to aphid infestation but a viral mutant unable to express the 2b protein (Fny-CMV∆2b) induces aphid resistance. We hypothesized that in tobacco, one or more of the four other Fny-CMV gene products (the 1a or 2a replication proteins, the movement protein, or the coat protein) are potential aphid resistance elicitors, whilst the 2b protein counteracts induction of aphid resistance. Mutation of the Fny-CMV 2b protein indicated that inhibition of virus-induced resistance to aphids (Myzus persicae) depends on amino acid sequences known to control nucleus-to-cytoplasm shuttling. LS-CMV (subgroup II) also increased susceptibility to aphid infestation but the LS-CMV∆2b mutant did not induce aphid resistance. Using reassortant viruses comprising different combinations of LS and Fny genomic RNAs, we showed that Fny-CMV RNA 1 but not LS-CMV RNA 1 conditions aphid resistance in tobacco, suggesting that the Fny-CMV 1a protein triggers resistance. However, the 2b proteins of both strains suppress aphid resistance, suggesting that the ability of 2b proteins to inhibit aphid resistance is conserved among divergent CMV strains.

Different Plant Viruses Induce Changes in Feeding Behavior of Specialist and Generalist Aphids on Common Bean That Are Likely to Enhance Virus Transmission

Bean common mosaic virus (BCMV), bean common mosaic necrosis virus (BCMNV), and cucumber mosaic virus (CMV) cause serious epidemics in common bean (Phaseolus vulgaris), a vital food security crop in many low-to-medium income countries, particularly in Sub-Saharan Africa. Aphids transmit these viruses "non-persistently," i.e., virions attach loosely to the insects' stylets. Viruses may manipulate aphid-host interactions to enhance transmission. We used direct observation and electrical penetration graph measurements to see if the three viruses induced similar or distinct changes in feeding behaviors of two aphid species, Aphis fabae and Myzus persicae. Both aphids vector BCMV, BCMNV, and CMV but A. fabae is a legume specialist (the dominant species in bean fields) while M. persicae is a generalist that feeds on and transmits viruses to diverse plant hosts. Aphids of both species commenced probing epidermal cells (behavior optimal for virus acquisition and inoculation) sooner on virus-infected plants than on mock-inoculated plants. Infection with CMV was especially disruptive of phloem feeding by the bean specialist aphid A. fabae. A. fabae also experienced mechanical stylet difficulty when feeding on virus-infected plants, and this was also exacerbated for M. persicae. Overall, feeding on virus-infected host plants by specialist and generalist aphids was affected in different ways but all three viruses induced similar effects on each aphid type. Specifically, non-specialist (M. persicae) aphids encountered increased stylet difficulties on plants infected with BCMV, BCMNV, or CMV, whereas specialist aphids (A. fabae) showed decreased phloem ingestion on infected plants. Probing and stylet pathway activity (which facilitate virus transmission) were not decreased by any of the viruses for either of the aphid species, except in the case of A. fabae on CMV-infected bean, where these activities were increased. Overall, these virus-induced changes in host-aphid interactions are likely to enhance non-persistent virus transmission, and data from this work will be useful in epidemiological modeling of non-persistent vectoring of viruses by aphids.

Modelling and manipulation of aphid-mediated spread of non-persistently transmitted viruses

Aphids vector many plant viruses in a non-persistent manner i.e., virus particles bind loosely to the insect mouthparts (stylet). This means that acquisition of virus particles from infected plants, and inoculation of uninfected plants by viruliferous aphids, are rapid processes that require only brief probes of the plant's epidermal cells. Virus infection alters plant biochemistry, which causes changes in emission of volatile organic compounds and altered accumulation of nutrients and defence compounds in host tissues. These virus-induced biochemical changes can influence the migration, settling and feeding behaviours of aphids. Working mainly with cucumber mosaic virus and several potyviruses, a number of research groups have noted that in some plants, virus infection engenders resistance to aphid settling (sometimes accompanied by emission of deceptively attractive volatiles, that can lead to exploratory penetration by aphids without settling). However, in certain other hosts, virus infection renders plants more susceptible to aphid colonisation. It has been suggested that induction of resistance to aphid settling encourages transmission of non-persistently transmitted viruses, while induction of susceptibility to settling retards transmission. However, recent mathematical modelling indicates that both virus-induced effects contribute to epidemic development at different scales. We have also investigated at the molecular level the processes leading to induction, by cucumber mosaic virus, of feeding deterrence versus susceptibility to aphid infestation. Both processes involve complex interactions between specific viral proteins and host factors, resulting in manipulation or suppression of the plant's immune networks.

Pathogenic modification of plants enhances long-distance dispersal of nonpersistently transmitted viruses to new hosts

Aphids spread the majority of plant viruses through nonpersistent transmission (NPT), whereby virus particles attach transiently to these insects’ probing mouthparts. Virus acquisition from infected plants and inoculation to healthy host plants is favored when aphids briefly probe plant epidermal cells. It is well established that NPT virus infection can alter plant–vector interactions, and, moreover, such pathogen modifications are found in a range of plant and animal systems. In particular, viruses can make plants more attractive to aphids but inhibit aphid settling on infected plants. It is hypothesized that this viral “reprogramming” of plants promotes virus acquisition and encourages dispersal of virus‐bearing aphids to fresh hosts. In contrast, it is hypothesized that virus‐induced biochemical changes encouraging prolonged feeding on infected hosts inhibit NPT. To understand how these virus‐induced modifications affect epidemics, we developed a modeling framework accounting for important but often neglected factors, including feeding behaviors (probing or prolonged feeding) and distinct spatial scales of transmission (as conditioned by wingless or winged aphids). Analysis of our models confirmed that when viruses inhibit aphid settling on infected plants this initially promotes virus transmission. However, initially enhanced transmission is self‐limiting because it decreases vector density. Another important finding is that virus‐induced changes encouraging settling will stimulate birth of winged aphids, which promotes epidemics of NPT viruses over greater distances. Thus our results illustrate how plant virus modifications influence epidemics by altering vector distribution, density, and even vector form. Our insights are important for understanding how pathogens in general propagate through natural plant communities and crops.

Viral Manipulation of Plant Stress Responses and Host Interactions With Insects

Do the alterations in plant defensive signaling and metabolism that occur in susceptible hosts following virus infection serve any purpose beyond directly aiding viruses to replicate and spread? Or indeed, are these modifications to host phenotype purely incidental consequences of virus infection? A growing body of data, in particular from studies of viruses vectored by whiteflies and aphids, indicates that viruses influence the efficiency of their own transmission by insect vectors and facilitate mutualistic relationships between viruses and their insect vectors. Furthermore, it appears that viruses may be able to increase the opportunity for transmission in the long term by providing reward to the host plants that they infect. This may be conditional, for example, by aiding host survival under conditions of drought or cold or, more surprisingly, by helping plants attract beneficial insects such as pollinators. In this chapter, we cover three main areas. First, we describe the molecular-level interactions governing viral manipulation of host plant biology. Second, we review evidence that virus-induced changes in plant phenotype enhance virus transmission. Finally, we discuss how direct and indirect manipulation of insects and plants might impact on the evolution of viruses and their hosts.

Premixed vs basal-bolus insulin regimen in Type 2 diabetes: comparison of clinical outcomes from randomized controlled trials and real-world data

AIM

To evaluate the concordance between data derived from randomized controlled trial (RCT) and real-world estimates of HbA_1c and weight change after 24 weeks of initiation of a basal-bolus compared with a premixed insulin regimen in people with Type 2 diabetes.

METHODS

Data eight RCTs were pooled after a systematic review of studies examining basal-bolus (n = 1893) or premixed (n = 1517) regimens. Real-world data were extracted from the UK primary care dataset for people on basal-bolus (n = 7483) or premixed insulin regimens (n=10 744). The mean differences between HbA_1c and weight from baseline were calculated using t-tests, while analysis of variance was used to compare the two treatment regimens. Linear regression analyses were used to determine the predictors of this change.

RESULTS

Both insulin regimens were associated with HbA_1c reductions (real-world data -0.28%; RCT data, -1.4%) and weight gain (real-world data, +0.27 kg; RCT data, +2.96 kg) but there were no significant differences between basal-bolus and premixed insulin. Discordances in the pattern of treatment response were observed, however, between real-world and RCT data for both insulin regimens. For any given baseline HbA_1c concentration, the change in HbA_1c in the RCTs was greater than in real-world conditions and for those with baseline weight above ~60 kg, RCT data showed overall weight gain in contrast to slight weight loss in the real-world population. Lastly, for both randomized controlled trial and real-world populations, while greater baseline weight was associated with reduced response to treatment, the association was much steeper in the RCT than in the real-world population. In addition, greater baseline weight was associated with greater weight reductions in both premixed insulin and basal-bolus insulin regimens, although to a lesser extent with the latter.

CONCLUSION

These results highlight specific discrepancies in the HbA_1c reduction and weight change in insulin regimen between real world versus RCT populations; with greater reduction in HbA_1c and greater increase in weight observed in the RCT population than in the real-world population. Also, the basal-bolus regimens in both real-world and RCT populations showed greater reduction in HbA_1c compared to the premix regimen (though more marked in RCTs), while the premix regimen showed greater increase in weight in real-world, as against basal-bolus in the RCT population.

Host lifespan and the evolution of resistance to multiple parasites

Hosts are typically challenged by multiple parasites, but to date theory on the evolution of resistance has mainly focused on single infections. We develop a series of models that examine the impact of multiple parasites on the evolution of resistance under the assumption that parasites coexist at the host population scale as a consequence of superinfection. In this way, we are able to explicitly examine the impact of ecological dynamics on the evolutionary outcome. We use our models to address a key question of how host lifespan affects investment in resistance to multiple parasites. We show that investment in costly resistance depends on the specificity of the immune response and on whether or not the focal parasite leads to more acute infection than the co-circulating parasite. A key finding is that investment in resistance always increases as the immune response becomes more general independently of whether it is the focal or the co-circulating parasite that exploits the host most aggressively. Long-lived hosts always invest more than short-lived hosts in both general resistance and resistance that is specific to relatively acute focal parasites. However, for specific resistance to parasites that are less acute than co-circulating parasites it is the short-lived hosts that are predicted to invest most. We show that these results apply whatever the mode of defence, that is whether it is through avoidance or through increased recovery, with or without acquired immunity, or through acquired immunity itself. As a whole, our results emphasize the importance of considering multiple parasites in determining optimal immune investment in eco-evolutionary systems.

Effect of diabetes on the cutaneous microcirculation of the feet in patients with intermittent claudication

AIMS

To evaluate endothelial-dependent and - independent cutaneous vasodilator responses in the feet of patients with peripheral arterial disease (PAD) with or without Type 2 diabetes.

METHODS

Cutaneous microvascular responses in the dorsum of both lower limbs were measured in the supine position using Laser Doppler Fluximetry combined with iontophoretic administration of endothelial-dependent (acetylcholine, Ach) and -independent (sodium nitroprusside, SNP) vasodilators in diabetic (n = 19) and non diabetic (n = 17) patients with PAD (presenting as unilateral calf intermittent claudication (IC).

RESULTS

In patients with diabetes and IC, endothelial-dependent vasodilation was significantly impaired in the symptomatic limb [74 (57,105) vs 68 (24,81) PU, Z =-2.79, p = 0.005] compared to the asymptomatic limb. Patients without diabetes showed no impairment of vasodilation. Resting ankle-brachial pressure index did not identify the presence of abnormalities in microvascular function.

CONCLUSIONS

The combination of diabetes and PAD is associated with a reduction in endothelial-dependent cutaneous vasodilation in the feet without an associated reduction in endothelial independent vasodilation.

Comparison of cardiovascular and metabolic outcomes in people with type 2 diabetes on insulin versus non-insulin glucose-lowering therapies (GLTs): A systematic review and meta-analysis of clinical trials

OBJECTIVES

To compare the cardiovascular and metabolic outcomes of Insulin versus non-insulin glucose lowering therapy (GLT).

METHODS

We included randomised control trials (RCTs) which randomised patients aged >18years with Type 2 Diabetes (T2D) to insulin vs non-insulin GLT. We used risk ratios (RR), risk difference (RD) and odds ratios (OR) with 95% confidence interval (95%CI) to analyse the treatment effects of dichotomous outcomes and mean differences (with 95% CI) for continuous outcomes.

RESULTS

We included 18 RCTs with 19,300 participants. There was no significant difference in the risk of all-cause mortality and CV events between the groups (RR=1.01; 95%CI: 0.96-1.06; p=0.69). In 16 trials, insulin showed greater efficacy in glycaemic control (mean diff=-0.20; 95%CI: -0.28 to -0.11) but the proportion achieving HbA1c level of either ⩽7.0% or 7.4% (53 or 57mmol/mol) was similar in both (OR=1.55; 95%CI=0.92-2.62). The non-insulin group had a significant reduction in weight (mean diff=-3.41; 95%CI: -4.50 to -2.32) and an increase in the proportion of adverse events (54.7% vs 45.3%, p=0.044), but the insulin group showed an (RR=1.90; 95%CI: 1.44-2.51) increased risk of hypoglycaemia.

CONCLUSION

There was no difference in the risk of all-cause mortality and adverse cardiovascular (CV) events between Insulin and non-insulin GLTs. Insulin was associated with superior reduction in HbA1c; least reduction in weight and higher risk of hypoglycaemia. Both showed similar proportion of patients achieving HbA1c target. Non-insulin GLTs were associated with a higher risk in reported adverse drug events.

Dynamics in insulin requirements and treatment safety

AIMS

The majority of insulin users have elevated HbA1c. There is growing recognition that the low success rates are due to variations in insulin requirements. Thus, frequent dosage adjustments are needed. In practice, adjustments occur sporadically due to limited provider availability. We investigated intra-individual dynamics of insulin requirements using data from a service evaluation of the d-Nav® Insulin Guidance Service. This service facilitates automated insulin dosage adjustments, as often as needed, to achieve and maintain optimal glycemic balance.

METHODS

Data were collected from subjects who have been using the service for more than a year. Events of considerable and persistent decrease in insulin requirements were identified by drops in total daily insulin ≥25%.

RESULTS

Overall, 62 patients were studied over an average period of 2.1±0.5 (mean±standard deviation) years. Stability in HbA1c was attained after ~3 quarters at 7.4%±0.2% (57.4mmol/mol±1mmol/mol). Events were identified in 56.5% of the patients. On average, each affected patient had 0.8±0.4 events per year, lasting 9.7±6.6weeks, while total daily insulin dosage decreased by 41.4±13.4%.

CONCLUSIONS

Our findings may call attention to a major contributing factor to hypoglycemia among insulin users. In reality, insulin dosage is seldom adjusted and thus transient periods of decrease in insulin requirements and overtreatment are usually overlooked.

Drug-Induced Diabetes Mellitus: Evidence for Statins and Other Drugs Affecting Glucose Metabolism

Abnormalities of glucose metabolism and glucose tolerance, either because of a reduction in tissue sensitivity to insulin (e.g., in liver, skeletal muscle, and adipose tissues) and/or a reduction in pancreatic insulin secretion, are associated with a number of unwanted health outcomes. Even small increases in circulating glucose levels (often described as dysglycemia or prediabetes) may confer an increased risk of cardiovascular (CV) disease and progression to overt type 2 diabetes. A number of drug therapies, many of them used long term in chronic disease management, have adverse effects on glucose metabolism, diabetes risk, and glycemic control among patients with preexisting diabetes. In this study, we review the evidence, underlying mechanisms, and the clinical significance of drug-related adverse effects on glucose metabolism.

The epidemiological feedbacks critical to the evolution of host immunity

We examine in detail how epidemiological feedbacks combine with costs and benefits to determine the evolution of resistance by systematically analysing continuously stable strategies (CSS) for different host-parasite frameworks. The mode of resistance (innate versus acquired), the nature of the host (i.e. life-history and immunological memory) and the nature of the disease (effects on fertility or mortality) all impact on the feedbacks that are critical to the evolution of resistance. By identifying relationships between CSS investment and the underlying epidemiological feedback for each mode of resistance in each framework, we distil complex feedbacks into simple combinations of selection pressures. When the parasite does not affect fertility, CSS investment reflects only the benefit of resistance and we explain why this is markedly different for innate and acquired resistance. If infection has no effect on host fertility, CSS investment in acquired immunity increases with the square of disease prevalence. While in contrast for evolving innate resistance, CSS investment is greatest at intermediate prevalence. When disease impacts fertility, only a fraction of the host population reproduce, and this introduces new ecological feedbacks to both the cost of resistance and the damage from infection. The multiple feedbacks in this case lead to the alternative result that the higher the abundance of infecteds, the higher the investment in innate resistance. A key insight is that maximal investment occurs at intermediate lifespans in a range of different host-parasite interactions, but for disparate reasons which can only be understood by a detailed analysis of the feedbacks. We discuss the extension of our approach to structured host populations and parasite community dynamics.

Seasonality selects for more acutely virulent parasites when virulence is density dependent

Host condition is often likely to influence parasite virulence. Furthermore, condition may often be correlated with host density, and therefore, it is important to understand the role of density-dependent virulence (DDV). We examine the consequences of DDV to the evolution of parasites in both seasonal and non-seasonal environments. In particular, we consider seasonality in host birth rate that results in a fluctuating host density and therefore a variable virulence. We show that parasites are selected for lower exploitation, and therefore lower transmission and virulence as the strength of DDV increases without seasonality. This is an important insight from our models; DDV has the opposite effect on the evolution of parasites to that of higher baseline mortality. Our key result is that although seasonality does not affect the evolution of virulence in classical models, with DDV parasites in seasonal environments are predicted to evolve to be more acute. This suggests that in more seasonal environments wildlife disease is likely to be more rather than less virulent if DDV is widespread.

Allelotype of non-small cell lung cancer

Loss of heterozygosity (LOH) studies have been used extensively to identify regions on chromosomes that may contain putative tumour suppressor genes. We have undertaken extensive allelotyping of 45 specimens of non-small cell lung cancer (NSCLC) using 92 polymorphic microsatellite markers on 39 chromosome arms. The most frequent allelic imbalances were found on chromosome arms 3p, 9p and 17p. Significant allelic imbalance was found on other chromosome arms including, 5q (21%), 8p (19%), 13q (24%) and 17q (18%). The LOH data on 3p was subdivided into the four chromosomal regions considered to contain putative tumour suppressor genes 3p25-p24 (10%), 3p21 (10%), 3p14 (25%) and 3p13-p12 (22%). The frequency of loss in the different regions on 9p were: 9pter-p23 (31%), 9p23-p22 (45%) and 9p21-cent (30%). LOH on 17p was separated into three regions: 17pter-p13 (9%), 17p13 (33%) and 17p13-cent (22%). No correlation was found between LOH on any of the chromosomal arms and any of the clinicopathological parameters such as pathology, level of differentiation, TNM staging or alcohol intake. Only one significant association was found between LOH and tumour types. A significant difference was found between LOH on 17q in adenocarcinomas and squamous cell carcinomas (p=0.037). The fractional allele loss (FAL) values for this group of 45 NSCLC gave a median value of 0.9 (range 0-0.45). No correlation was found between FAL and nodes at pathology (p>0.05) and between FAL and tumour grade (p>0.05). No correlation was found between p53 or ras mutations in these NSCLC specimens and their FAL values. Accumulated genetic damage, as provided by this allelotype analysis, provides a useful molecular parameter by which to assess NSCLC and may, in time, assist in the determination of the clinical behaviour and clinical outcome of these tumours.

Assessment of lower limb microcirculation: exploring the reproducibility and clinical application of laser Doppler techniques

PURPOSE OF STUDY

Non-invasive laser Doppler fluximetry (LDF) and laser Doppler imaging (LDI), combined with iontophoresis, have been used to study the microcirculation in a range of clinical conditions including lower limb venous disease. A prerequisite for an accurate measurement tool is that it is reproducible. However, there is currently no literature with respect to the reproducibility of LDF and LDI combined with iontophoresis in the lower limb (in general) and in the upright position (in specific). Furthermore, the two techniques have been used interchangeably by researchers and the association between these two different measurement methods has not been explored, nor have the factors that affect them been well described. Thus the aim of this study was to determine the reproducibility of LDF and LDI with iontophoresis in the lower limb and investigate factors that influence their clinical application.

PROCEDURES

Cutaneous microvascular responses in the lower limb were measured in the supine and standing positions using LDF and LDI combined with iontophoretic administration of endothelial-dependent (acetylcholine, ACh) and -independent (sodium nitroprusside) vasodilators in 25 patients with uncomplicated isolated superficial venous incompetence (ISVI) and 26 healthy controls.

RESULTS

Maximum perfusion had the best reproducibility assessed by LDF (CV 20.5-24.3%) and LDI (15.8-17.6%). Both techniques were positively influenced by iontophoretic dose (e.g. p = 0.0001 for LDF) and the use of vasodilator agents (e.g. p = 0.0001 for LDF), but negatively influenced in the standing position and/or in the presence of ISVI (p = 0.0016 and 0.045, respectively, for LDF). There was a statistically significant positive relationship between the two techniques, for example ACh maximum perfusion versus LDF ACh maximum perfusion (r = 0.404, p = 0.016).

CONCLUSIONS

Both techniques are reproducible, in line with similar studies undertaken in other areas of the human body, and provide useful information for the study of the lower-limb microcirculation. Direct comparison between techniques based on absolute numbers should be avoided and the technique choice should be based on individual study needs.

Exenatide compared with long-acting insulin to achieve glycaemic control with minimal weight gain in patients with type 2 diabetes: results of the Helping Evaluate Exenatide in patients with diabetes compared with Long-Acting insulin (HEELA) study

AIM

The Helping Evaluate Exenatide in overweight patients with diabetes compared with Long-Acting insulin (HEELA) study was designed to examine whether the glucagon-like peptide-1 (GLP-1) receptor agonist, exenatide, could improve HbA1c (< or =7.4%) with minimal weight gain (< or =1 kg) compared with insulin glargine.

METHODS

Patients [body mass index (BMI) >27 kg/m(2)] with elevated cardiovascular risk and type 2 diabetes inadequately controlled on two or three oral antidiabetes drugs (OADs) were randomized to add-on exenatide 5-10 microg b.i.d. (n = 118) or insulin glargine o.d. (titrated to target fasting plasma glucose < or =5.6 mmol/l; n = 117) for 26 weeks.

RESULTS

The study population had baseline mean (s.d.) age of 56.5 (9.1) years and BMI of 34.1 (5.3) kg/m(2), and 58.5% of patients were taking two OADs. Mean baseline HbA1c was 8.65 (0.68)% in the exenatide group and 8.48 (0.66)% in the insulin glargine group. The proportions of patients achieving the composite endpoint of HbA1c < or =7.4% with weight gain < or =1 kg were 53.4% for the exenatide group and 19.8% for the insulin glargine group (p < 0.001 for exenatide vs. insulin glargine). Exenatide and insulin glargine did not demonstrate a significant difference in HbA1c improvements [least square (LS) mean [s.e.m.]: -1.25 [0.09]% and -1.26 [0.09]% respectively; p = 0.924], but had divergent effects on body weight (-2.73 [0.31] vs. +2.98 [0.31] kg respectively, p < 0.001) after 26 weeks. There were more treatment-related adverse events with exenatide but a lower incidence of nocturnal hypoglycaemia, with no differences in overall or severe hypoglycaemia.

CONCLUSIONS

Additional treatment with exenatide resulted in significantly more overweight and obese patients with an elevated cardiovascular risk and type 2 diabetes achieving better glycaemic control with minimal weight gain compared with insulin glargine.

Antihypertensive efficacy of indapamide SR in hypertensive patients uncontrolled with a background therapy: the NATIVE study

OBJECTIVES

Antihypertensive monotherapy rarely achieves blood pressure (BP) control. NATIVE (NATrilix SR use in combInation antihypertensiVe thErapy) evaluated indapamide sustained release (SR) in hypertensive patients receiving background therapy.

RESEARCH DESIGN AND METHODS

Patients remaining hypertensive (systolic BP [SBP], 145-180 mmHg; diastolic BP [DBP], 95-105 mmHg) while receiving an angiotensin-converting enzyme (ACE) inhibitor (n = 709), beta-blocker (n = 629), calcium-channel blocker (CCB; n = 493), angiotensin II type 1 receptor blocker (ARB; n = 75), alpha-blocker (n = 29) or other therapy (n = 6) were enrolled, recruited by physicians from 228 centres in Pakistan. Indapamide SR 1.5 mg was administered daily for 3 months with background therapy. BP was assessed every 2 weeks, and blood glucose and total cholesterol were evaluated at baseline and study end in a patient subgroup. Adverse events were also recorded.

MAIN OUTCOME MEASURES AND RESULTS

Of 2073 enrolled patients (49% males; mean age 51 years), 1941 received indapamide SR and background therapy. SBP and DBP decreased significantly (SBP, 166 +/- 16 mmHg at baseline vs. 132 +/- 12 mmHg at 3 months; DBP, 102 +/- 8 mmHg vs. 83 +/- 6 mmHg; both p < 0.0001 vs. baseline). Patients uncontrolled with an ACE inhibitor, beta-blocker, CCB or ARB achieved an SBP/DBP decrease of 34 +/- 15/19 +/- 9, 33 +/- 17/19 +/- 10, 33 +/- 15/18 +/- 8 or 35 +/- 16/20 +/- 12 mmHg, respectively (all p < 0.0001). In all, 84% of patients achieved target SBP (< or = 140 mmHg) and 61% achieved BP normalisation (SBP < 140, DBP < 90 mmHg). The absence of placebo control may lead to an overestimation of the extent of the BP reduction achieved. Glucose and cholesterol levels were unaffected by indapamide SR. Four percent of patients experienced side-effects, which were mild-to-moderate in severity.

CONCLUSIONS

In patients with hypertension despite antihypertensive therapy, indapamide SR significantly reduced BP with a good acceptability profile. Indapamide SR may represent an effective additional therapy for patients who do not achieve BP goals with other antihypertensive agents.

Medical Therapy for Intermittent Claudication

Medical therapy to improve symptoms, stabilise the underlying vascular disease and improve lower limb outcomes is an important and effective adjunct to lifestyle modification and surgical or endovascular interventions in patients with IC. Randomised placebo controlled trials have shown that the phosphodiesterase III inhibitor cilostazol 100mg bid improves pain-free and maximum walking distance, as well as quality of life, in a range of patients with intermittent claudication in whom there is no evidence of tissue necrosis or rest pain. This review summarises the evidence from 8 pivotal trials of cilostazol involving over 2000 patients with intermittent claudication treated for up to 6 months. There is comparatively less evidence to support the use of other treatment modalities for relief of symptoms in intermittent claudication, but there is considerable interest in therapeutic angiogenesis to promote new vessel formation and enhance collateralisation of the lower limb using recombinant growth factor proteins or gene transfer strategies. The rationale for therapeutic angiogenesis is discussed, together with the most recent results from randomised trials in patients with peripheral arterial disease.

Effect of pioglitazone on the drivers of cardiovascular risk in type 2 diabetes

The prevalence of type 2 diabetes and its associated mortality and morbidity are continuing to increase across the world. People with type 2 diabetes typically have a cluster of risk factors for cardiovascular disease, including hyperglycaemia, hypertension and lipid abnormalities, which contribute to the high cardiovascular morbidity and mortality in these patients. Targets for glycosylated haemoglobin, lipids and blood pressure are becoming more stringent, and most patients will require multiple therapies to maximally reduce cardiovascular risk. In a large randomised, controlled, long-term cardiovascular outcomes study pioglitazone showed durable glycaemic control, a powerful insulin-sparing effect and changes in the lipid profile associated with reduced cardiovascular risk. This article reviews these metabolic findings in the context of previous randomised, controlled studies for pioglitazone and discusses whether the integration of this agent into the treatment regimen of appropriate patient groups has the potential to improve cardiovascular outcomes in type 2 diabetes.

Contrasting Effects of Varicose Vein Surgery on Endothelial-dependent and -independent Cutaneous Vasodilation in the Perimalleolar Region

OBJECTIVES

To evaluate the effects of varicose vein surgery on cutaneous microvascular perfusion and vasodilator responses to acetylcholine (Ach) and sodium nitroprusside (SNP) in the gaiter area of patients with great saphenous vein insufficiency.

METHODS

Twenty-nine patients with isolated great saphenous vein incompetence attended three study mornings (before surgery, and 6-8 weeks and 6 months after sapheno-femoral ligation+partial stripping) during which cutaneous microvascular responses were measured in the supine and standing positions using laser Doppler fluximetry (LDF) combined with incremental-dose iontophoretic administration of endothelial-dependent (Ach) and -independent (SNP) vasodilators.

RESULTS

Varicose vein surgery had no significant effect on baseline cutaneous perfusion or the microvascular response to Ach: e.g. peak vasodilator responses to the 1000 microC stimulus were mean 58 SEM 7, 64 SEM 6 and 65 SEM 7PU on the pre-operative, 6-8 weeks and 6 months assessments. In contrast, the corresponding responses to SNP were significantly increased following surgery: e.g. at 2000 microC, mean 63 SEM 9, 142 SEM 4 and 157 SEM 9PU (p<0.0001) in the upright position.

CONCLUSIONS

Sapheno-femoral ligation and partial stripping in patients with great saphenous vein insufficiency improves endothelial-independent cutaneous vasodilator function at the gaiter area, which may at least partly explain the benefits of surgery in reducing the risk of venous ulceration.

Does temporal artery biopsy influence the management of temporal arteritis?

BACKGROUND

Temporal arteritis (TA) is the commonest form of primary vasculitis. Symptoms are variable, and therefore the diagnosis (or exclusion) of TA is often difficult. Surgeons are frequently asked to perform a temporal artery biopsy (TAB), but whether the histological result actually influences clinical management is unclear.

AIM

To assess whether, in routine clinical practice, a TAB affects clinical decision-making in patients with suspected TA.

DESIGN

Retrospective audit.

METHODS

All patients who underwent a TAB in a single hospital over a 2-year period were identified. This included patients referred from different specialist departments. Individual patient records were examined to document the TAB result, and in particular, the timings of commencement and discontinuation of corticosteroid therapy.

RESULTS

A total of 44 patients were included. TAB was positive in seven patients and negative in 37. In 31, there was no change in their clinical management despite a negative biopsy result: 18 continued with corticosteroids for >6 months with a clinical diagnosis of TA, and in 13 patients a decision to stop steroids, or an alternative diagnosis, was made before the biopsy result was known.

DISCUSSION

In this retrospective study, only a small number of TABs provided positive histological confirmation of TA, and in most patients undergoing TAB, there was little evidence that clinical decision-making with respect to corticosteroid therapy was influenced by the TAB result.

Effects of metformin and oleic acid on adipocyte expression of resistin

AIM

The adipocyte-secreted hormone resistin has been implicated in obesity-induced insulin resistance and type 2 diabetes, but pharmacological and dietary factors that regulate resistin gene expression and the effects of resistin on cellular glucose uptake in muscle have not been clearly defined.

METHODS

Expression of resistin mRNA was studied in differentiated 3T3-L1 adipocytes by using real-time semiquantitative reverse transcription-polymerase chain reaction. The effects of resistin on insulin-stimulated and insulin-independent 2-deoxyglucose uptake were evaluated in L6 muscle cells.

RESULTS

Insulin 1 microm and rosiglitazone 10 microm markedly reduced resistin mRNA expression (relative to the control gene TF2D) by 4.7-fold (p < 0.05) and 5.3-fold (p < 0.02), respectively. Similar reductions in resistin mRNA were demonstrated with metformin 100 microm (6.2-fold reduction, p < 0.02) and oleic acid 100 microm (3.9-fold reduction, p < 0.03). Resistin 1 microm significantly reduced maximum insulin-stimulated 2-deoxyglucose uptake in L6 cells from 634 to 383% (relative to 100% for control, p < 0.001), and co-administration of rosiglitazone had no effect on resistin-induced insulin resistance. In the absence of insulin, however, resistin increased glucose uptake dose-dependently (e.g., 1.75-fold at 5 microm, p < 0.001) via a mitogen-activated protein kinase-dependent pathway.

CONCLUSIONS

These results demonstrate that various glucose-lowering therapies and oleic acid reduce resistin gene expression in isolated adipocytes, and that resistin impairs insulin-stimulated glucose uptake in skeletal muscle-derived cells.

Occupational asthma after exposure to plaster casts containing methylene diphenyl diisocyanate

BACKGROUND

The case of a 34-year-old female nurse is presented. She worked in an accident and emergency department in a district general hospital, with methylene diphenyl diisocyanate (MDI)-containing synthetic plaster casts. She worked with MDI on a daily basis for 4 years. She was out of the department for 1 year and on her return developed cough, wheeze and dyspnoea within 5 min of exposure to MDI- containing synthetic casts.

METHOD

A bronchial provocation test was performed and confirmed an early asthmatic response.

RESULTS

There was a 39% decrease in the forced expiratory volume in 1 s 15 min after exposure, which required the administration of a bronchodilator on two occasions. The patient has subsequently avoided MDI-containing synthetic plaster casts and has experienced no further respiratory symptoms.

CONCLUSION

This case illustrates that respiratory sensitization can occur as a result of exposure to MDI-containing synthetic casts and highlights the need for vigilance when health care workers are using isocyanate-containing synthetic casts.

The role of cilostazol in the treatment of intermittent claudication

This paper represents a review, by experts, of current opinion and information on intermittent claudication (IC) and the role that cilostazol plays in its treatment. IC is a common and debilitating condition that has a significant adverse impact on health-related quality of life (HR-QoL). It is currently under-recognised as a powerful marker of increased cardiovascular (CV) risk. The clinical priority is secondary prevention -- sometimes referred to as best medical therapy aimed at reducing CV risk. However, the priority for most patients (often overlooked by clinicians) is symptom relief: an increase in walking distance leading to an improvement in HR-QoL. The symptoms of IC may be improved by exercise, pharmacotherapy, and when these are unsuitable or unsuccessful, endovascular or surgical intervention. Cilostazol is indicated for the improvement of maximal and pain-free walking distance in patients with IC who do not have rest pain or tissue necrosis. In clinical trials, cilostazol improved symptoms both objectively and subjectively, and also improved HR-QoL. Cilostazol is usually well tolerated, with adverse events being generally mild to moderate in intensity, and transient or resolved after symptomatic treatment (e.g. non-prescription analgesics). Such events only infrequently require permanent drug withdrawal. There are no interactions with other drugs commonly prescribed in patients with IC, such as statins and anti-platelet agents. Cilostazol also has a range of potentially beneficial effects that may in the future be proven to decrease CV risk and modify the underlying process of atherosclerosis. Cilostazol represents the best evidence-based pharmacological therapy available for the symptoms of IC and should be the first-line treatment for symptom improvement in appropriate patients. Based on the available treatment strategies, the paper presents a suggested algorithm for the management of IC highlighting the role of cilostazol.

Therapeutic Angiogenesis in Peripheral Arterial Disease: Can Biotechnology Produce an Effective Collateral Circulation?

The physiological processes of angiogenesis, vasculogenesis and arteriogenesis contribute to the growth of collateral vessels in response to obstructive arterial disease causing lower limb or myocardial ischaemia, but in clinical practice the endogenous angiogenic response is often suboptimal or impaired, e.g. by factors such as ageing, diabetes or drug therapies. Therapeutic angiogenesis is an application of biotechnology to stimulate new vessel formation via local administration of pro-angiogenic growth factors in the form of recombinant protein or gene therapy, or by implantation of endothelial progenitor cells that will synthesize multiple angiogenic cytokines. Numerous experimental and clinical studies have sought to establish 'proof of concept' for therapeutic angiogenesis in PAD and myocardial ischaemia using different treatment modalities, but the results have been inconsistent. This review summarises the mechanisms of angiogenesis and the results of recent trials evaluating the efficacy and safety of different gene therapy, recombinant protein and cellular-based treatment approaches to enhance collateral vessel formation.