Efficacy and safety of vericiguat in patients with HFrEF treated with sacubitril/valsartan: results from the VICTORIA trial

Background

In the VICTORIA trial (n=5050) the reduction in the primary composite endpoint of cardiovascular death (CVD) or heart failure hospitalization (HFH) was similar whether or not patients received sacubitril/valsartan. The distribution of those patients who received sacubitril/valsartan after randomization (drop-ins) and the relationship to the efficacy and safety of vericiguat is unknown.

Purpose

We assessed the efficacy and safety of vericiguat in patients who were or were not treated with sacubitril/valsartan at baseline in the VICTORIA trial and the implications of post- randomization use of sacubitril/valsartan.

Methods

A total of 5040 patients were analyzed according sacubitril/valsartan use at randomization or initiated after randomization. The efficacy of vericiguat on the primary composite endpoint and its components, time to first HF hospitalization or all-cause mortality, were assessed according to sacubitril/valsartan use. Safety outcomes included symptomatic hypotension, syncope, worsening renal function, and hyperkalemia.

Results

Overall, 731 patients (360 on vericiguat and 371 on placebo) received sacubitril/valsartan at randomization. Patients treated with sacubitril/valsartan were twice as likely to be from Western Europe or North America, to have a lower ejection fraction and systolic and diastolic blood pressures, were more often on triple therapy (65.9 vs 58.6%), and more likely to have received biventricular pacing (17.9 vs 14.1%) or ICDs (42.3 vs 25.3%). For patients on sacubitril/valsartan at baseline, the adjusted hazard ratios for vericiguat's treatment effect on the primary composite outcome, CVD, and HFH was 0.94 (95% CI 0.74–1.20), 0.81 (95% CI 0.55–1.20) and 0.99 (95% CI 0.76–1.30), respectively. For those patients not on sacubitril/valsartan (2161 vericiguat; 2148 on placebo), the corresponding adjusted hazard ratios for vericiguat's treatment effect on the primary composite outcome, CVD, and HFH were 0.89 (0.80–0.98), 0.95 (0.82–1.11), and 0,87 (0.78–0.98), respectively. There was no significant interaction on the treatment effect of vericiguat based on the use of sacubitril/valsartan. More placebo patients (n=238) received drop-in use of sacubitril/valsartan than vericiguat group (n=187; p=0.007) post-randomization during follow-up (Figure). Overall, adverse events in the 992 patients receiving sacubitril/valsartan (at either baseline or drop-in for at least 3 months) were not significantly different according to those on placebo vs vericiguat for symptomatic hypotension (21.0% vs 23.1), renal dysfunction (8.0 vs 9.0%), and hyperkalemia (10.3 vs 7.9%).

Conclusions

Sacubitril/valsartan use was initiated more frequently after randomization in patients on placebo than on vericiguat. Concomitant use of sacubitril/valsartan did not alter the efficacy of vericiguat and was similarly tolerated in both study arms.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): Merck & Co., Inc. and Bayer

Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm

We present the first results of the Fermilab National Accelerator Laboratory (FNAL) Muon g-2 Experiment for the positive muon magnetic anomaly a_{μ}≡(g_{μ}-2)/2. The anomaly is determined from the precision measurements of two angular frequencies. Intensity variation of high-energy positrons from muon decays directly encodes the difference frequency ω_{a} between the spin-precession and cyclotron frequencies for polarized muons in a magnetic storage ring. The storage ring magnetic field is measured using nuclear magnetic resonance probes calibrated in terms of the equivalent proton spin precession frequency ω[over ˜]_{p}^{'} in a spherical water sample at 34.7 °C. The ratio ω_{a}/ω[over ˜]_{p}^{'}, together with known fundamental constants, determines a_{μ}(FNAL)=116 592 040(54)×10^{-11} (0.46 ppm). The result is 3.3 standard deviations greater than the standard model prediction and is in excellent agreement with the previous Brookhaven National Laboratory (BNL) E821 measurement. After combination with previous measurements of both μ^{+} and μ^{-}, the new experimental average of a_{μ}(Exp)=116 592 061(41)×10^{-11} (0.35 ppm) increases the tension between experiment and theory to 4.2 standard deviations.

Atrial fibrillation and the prognostic performance of biomarkers in heart failure

Background

Consideration of circulating biomarkers for risk stratification in heart failure (HF) is recommended in authoritative international guidelines but the influence of atrial fibrillation (AF) on the prognostic performance of many markers is unclear. Therefore we investigated the interactions between AF and biomarkers in prediction of important clinical outcomes in HF.

Methods

NT-proBNP, pro-atrial natriuretic peptide (MR-proANP), C-type natriuretic peptide (CNP), NT-proCNP, high-sensitivity troponin-T, high-sensitivity troponin-I, mid-regional-propeptide adrenomedullin (MR-proADM), co-peptin (PAVP), growth differentiation factor-15 (GDF-15), sST2, Galectin-3 and procalcitonin levels were measured in a prospectively designed, multicenter, longitudinal study of adults with HF. AF was defined as a documented history of AF based on medical records, and/or presence of AF/atrial flutter on baseline 12-lead ECG. The primary outcome considered was the composite of HF-hospitalization or all-cause mortality on prospective follow-up at 2-years. Cox proportional-hazards models were used in the prognostic evaluation of biomarkers, and each was tested for interaction with AF.

Results

Among 1,099 patients with HF (mean age 62±12 years, 28% female, mean left ventricular ejection fraction 35±16%), 261 (24%) patients had AF. Median levels of NT-proBNP, GDF-15, ST2, MR-proADM, proANP and CNP were higher in AF (p<0.05). Above-median levels of all 12 biomarkers were independently associated with increased risk of the primary outcome. Significant interactions with AF were detected for Galectin-3 and sST2. Galectin-3 (>7.7ng/mL) was associated with increased HF-hospitalizations (adjusted hazard ratio [AHR] 1.75, 95% C.I. 1.10–2.77) and all-cause mortality (AHR 1.95, 95% C.I. 1.04–3.63) only among patients with AF. The prognostic performance of sST2 (>35.6ng/mL) was also stronger in AF especially for the primary outcome (AF: AHR 2.06 95% C.I. 1.32–3.21; non-AF: AHR 1.49 95% C.I. 1.18–1.88) and HF-hospitalization (AF: AHR 1.65, 95% C.I. 1.01–2.69; non-AF: AHR 1.32, 95% C.I. 1.02–1.71). The association of Galectin-3 with the composite outcome was not modified by HF type (HFpEF vs HFrEF) (p for 3-way interaction=0.61) except for sST2 (p for 3-way interaction=0.018) where the association appeared stronger in patients with HFpEF and AF (HR 3.12, 95% C.I. 1.26–7.78) compared to those with HFrEF and AF (HR 1.83, 95% C.I. 1.01–3.33) although numbers of events in each subgroup were small. Notably, no such interactions were observed for the most frequently measured prognostic markers in HF including NT-proBNP and the high-sensitivity cardiac troponins.

Conclusion

AF modified the prognostic utility of guideline-endorsed HF-biomarkers, wherein prognostic associations of Galectin-3 and ST2 were limited to, or stronger in, patients with AF. Application of markers for prognostic purposes in HF requires consideration of the presence or absence of AF.

Figure 1

Funding Acknowledgement

Type of funding source: Public hospital(s). Main funding source(s): National Medical Research Council of Singapore

Targeted inhibition of activated protein C by a non-active-site inhibitory antibody to treat hemophilia

Activated protein C (APC) is a plasma serine protease with antithrombotic and cytoprotective functions. Based on the hypothesis that specific inhibition of APC’s anticoagulant but not its cytoprotective activity can be beneficial for hemophilia therapy, 2 types of inhibitory monoclonal antibodies (mAbs) are tested: A type I active-site binding mAb and a type II mAb binding to an exosite on APC (required for anticoagulant activity) as shown by X-ray crystallography. Both mAbs increase thrombin generation and promote plasma clotting. Type I blocks all APC activities, whereas type II preserves APC’s cytoprotective function. In normal monkeys, type I causes many adverse effects including animal death. In contrast, type II is well-tolerated in normal monkeys and shows both acute and prophylactic dose-dependent efficacy in hemophilic monkeys. Our data show that the type II mAb can specifically inhibit APC’s anticoagulant function without compromising its cytoprotective function and offers superior therapeutic opportunities for hemophilia.

Activated protein C (APC) is a plasma serine protease with antithrombotic and cytoprotective functions. Here, the authors develop a monoclonal antibody that specifically inhibits APC’s anticoagulant function without compromising its cytoprotective function, and shows efficacy in animal models.

Effect of drug dose and timing of treatment on the emergence of drug resistance in vivo in a malaria model

BACKGROUND AND OBJECTIVES

There is a significant interest in identifying clinically effective drug treatment regimens that minimize the de novo evolution of antimicrobial resistance in pathogen populations. However, in vivo studies that vary treatment regimens and directly measure drug resistance evolution are rare. Here, we experimentally investigate the role of drug dose and treatment timing on resistance evolution in an animal model.

METHODOLOGY

In a series of experiments, we measured the emergence of atovaquone-resistant mutants of Plasmodium chabaudi in laboratory mice, as a function of dose or timing of treatment (day post-infection) with the antimalarial drug atovaquone.

RESULTS

The likelihood of high-level resistance emergence increased with atovaquone dose. When varying the timing of treatment, treating either very early or late in infection reduced the risk of resistance. When we varied starting inoculum, resistance was more likely at intermediate inoculum sizes, which correlated with the largest population sizes at time of treatment.

CONCLUSIONS AND IMPLICATIONS

(i) Higher doses do not always minimize resistance emergence and can promote the emergence of high-level resistance. (ii) Altering treatment timing affects the risk of resistance emergence, likely due to the size of the population at the time of treatment, although we did not test the effect of immunity whose influence may have been important in the case of late treatment. (iii) Finding the 'right' dose and 'right' time to maximize clinical gains and limit resistance emergence can vary depending on biological context and was non-trivial even in our simplified experiments.

LAY SUMMARY

In a mouse model of malaria, higher drug doses led to increases in drug resistance. The timing of drug treatment also impacted resistance emergence, likely due to the size of the population at the time of treatment.

Critical care usage after major gastrointestinal and liver surgery: a prospective, multicentre observational study

BACKGROUND

Patient selection for critical care admission must balance patient safety with optimal resource allocation. This study aimed to determine the relationship between critical care admission, and postoperative mortality after abdominal surgery.

METHODS

This prespecified secondary analysis of a multicentre, prospective, observational study included consecutive patients enrolled in the DISCOVER study from UK and Republic of Ireland undergoing major gastrointestinal and liver surgery between October and December 2014. The primary outcome was 30-day mortality. Multivariate logistic regression was used to explore associations between critical care admission (planned and unplanned) and mortality, and inter-centre variation in critical care admission after emergency laparotomy.

RESULTS

Of 4529 patients included, 37.8% (n=1713) underwent planned critical care admissions from theatre. Some 3.1% (n=86/2816) admitted to ward-level care subsequently underwent unplanned critical care admission. Overall 30-day mortality was 2.9% (n=133/4519), and the risk-adjusted association between 30-day mortality and critical care admission was higher in unplanned [odds ratio (OR): 8.65, 95% confidence interval (CI): 3.51-19.97) than planned admissions (OR: 2.32, 95% CI: 1.43-3.85). Some 26.7% of patients (n=1210/4529) underwent emergency laparotomies. After adjustment, 49.3% (95% CI: 46.8-51.9%, P<0.001) were predicted to have planned critical care admissions, with 7% (n=10/145) of centres outside the 95% CI.

CONCLUSIONS

After risk adjustment, no 30-day survival benefit was identified for either planned or unplanned postoperative admissions to critical care within this cohort. This likely represents appropriate admission of the highest-risk patients. Planned admissions in selected, intermediate-risk patients may present a strategy to mitigate the risk of unplanned admission. Substantial inter-centre variation exists in planned critical care admissions after emergency laparotomies.

The effect of bitewing radiography on estimates of dental caries experience among children differs according to their disease experience

BACKGROUND

Radiography is a regularly used and accepted adjunct to visual examination in the diagnosis of dental caries. It is assumed that not using radiographs can lead to underestimation of dental caries experience with most reports having involved studies of young adults or adolescents, and been focused on the permanent dentition. The aim of this study was to determine the relative contributions of bitewing radiography and clinical examination in the detection of dental caries in primary molars and to determine whether those contributions differ according to caries experience.

METHODS

A cross-sectional study was conducted, involving examinations undertaken in dental clinics. Bitewing radiographs taken at the time of the clinical examination were developed and read later, with the data from those used at the analysis stage to adjust the caries diagnosis for the mesial, occlusal and distal surfaces of the primary molar teeth. Children's clinically determined dmfs score was used to allocate them to one of three caries experience groups (0 dmfs, 1-8 dmfs, or 9+ dmfs).

RESULTS

Of the 501 three-to-eight-year-old children examined, nearly three-quarters were younger than six. Caries prevalence and mean dmfs after clinical examination alone and following radiographs were 63.1% and 4.6 (sd, 6.2), and 74.7% and 5.8 (sd, 6.5) respectively. Among children with a dmfs of 1-8, the number of lesions missed during the clinical examination was greater than the number of 106 (25.6%) in children with a dmfs of 9+. In the 185 children with no apparent caries at clinical examination, 124 lesions were detected radiographically, among 58 (46.8%) of those.

CONCLUSIONS

Taking bitewing radiographs in young children is not without challenges or risks, and it must be undertaken with these in mind. Diagnostic yields from bitewing radiographs are greater for children with greater caries experience. The findings of this study further support the need to consider using bitewing radiographs in young children to enhance the management of lesions not detected by a simple visual examination alone.

TRIAL REGISTRATION

ACTRN12614000844640 .

Blockade of placental growth factor reduces vaso-occlusive complications in murine models of sickle cell disease

Vaso-occlusive crisis (VOC) is the most common and debilitating complication of sickle cell disease (SCD); recurrent episodes cause organ damage and contribute to early mortality. Plasma placental growth factor (PlGF) levels are elevated in SCD and can further increase under hypoxic conditions in SCD mice. Treatment with a PlGF-neutralizing antibody (anti-PlGF Ab) in SCD mice reduced levels of monocyte chemoattractant protein-3, eotaxin, macrophage colony-stimulating factor, and plasminogen activator inhibitor-1 significantly, and of macrophage-derived chemokine and macrophage inflammatory protein-3β moderately; this may contribute to inhibition of leukocyte recruitment, activation, and thrombosis. In subsequent experiments, anti-PlGF Ab treatment significantly reduced plasma lactate dehydrogenase levels, indicating possible reduction in cellular destruction and/or hemolysis. Histopathology studies revealed decreased incidence and severity of congestion in the lungs and spleen with repeated anti-PlGF Ab treatment. Furthermore, anti-PlGF Ab significantly reduced vaso-occlusion events under hypoxic conditions in a modified dorsal skinfold chamber model in SCD mice. Therefore, elevated PlGF levels may contribute to recruitment and activation of leukocytes. This can subsequently lead to increased pathology of affected organs in addition to mediating acute hypoxia/reoxygenation-triggered vaso-occlusion under SCD conditions. Thus, targeting PlGF may offer a therapeutic approach to reduce acute VOC and possibly alleviate long-term vascular complications in patients with SCD.

The impact of fatigue on the non-technical skills performance of critical care air ambulance clinicians

BACKGROUND

The relationship between fatigue-related risk and impaired clinical performance is not entirely clear. Non-technical factors represent an important component of clinical performance and may be sensitive to the effects of fatigue. The hypothesis was that the sum score of overall non-technical performance is degraded by fatigue.

METHODS

Nineteen physicians undertook two different simulated air ambulance missions, once when rested, and once when fatigued (randomised crossover design). Trained assessors blinded to participants' fatigue status performed detailed structured assessments based on expected behaviours in four non-technical skills domains: teamwork, situational awareness, task management, and decision making. Participants also provided self-ratings of their performance. The primary endpoint was the sum score of overall non-technical performance.

RESULTS

The main finding, the overall non-technical skills performance rating of the clinicians, was better in rested than fatigued states (mean difference with 95% CI, 2.8 [2.2-3.4]). The findings remained consistent across individual non-technical skills domains; also when controlling for an order effect and examining the impact of a number of possible covariates. There was no difference in self-ratings of clinical performance between rested and fatigued states.

CONCLUSION

Non-technical performance of critical care air transfer clinicians is degraded when they are fatigued. Fatigued clinicians may fail to recognise the degree to which their performance is compromised. These findings represent risk to clinical care quality and patient safety in the dynamic and isolated environment of air ambulance transfer.

Clot stability as a determinant of effective factor VIII replacement in hemophilia A

Background

Factor VIII (FVIII) replacement is standard of care for patients with hemophilia A (HemA); however, patient response does not always correlate with FVIII levels. We hypothesize this may be in part due to the physical properties of clots and contributions of fibrin, platelets, and erythrocytes, which may be important for hemostasis.

Objective

To understand how FVIII contributes to effective hemostasis in terms of clot structure and mechanical properties.

Patients/Methods

In vitro HemA clots in human plasma or whole blood were analyzed using turbidity waveform analysis, confocal microscopy, and rheometry with or without added FVIII. In vivo clots from saphenous vein puncture in wild-type and HemA mice with varying FVIII levels were examined using scanning electron microscopy.

Results

FVIII profoundly affected HemA clot structure and physical properties; added FVIII converted the open and porous fibrin meshwork and low stiffness of HemA clots to a highly branched and dense meshwork with higher stiffness. Platelets and erythrocytes incorporated into clots modulated clot properties. The clots formed in the mouse saphenous vein model contained variable amounts of compressed erythrocytes (polyhedrocytes), fibrin, and platelets depending on the levels of FVIII, correlating with bleeding times. FVIII effects on clot characteristics were dose-dependent and reached a maximum at ~25% FVIII, such that HemA clots formed with this level of FVIII resembled clots from unaffected controls.

Conclusions

Effective clot formation can be achieved in HemA by replacement therapy, which alters the architecture of the fibrin network and associated cells, thus increasing clot stiffness and decreasing clot permeability.

Understanding genetic variation in in vivo tolerance to artesunate: implications for treatment efficacy and resistance monitoring

Artemisinin-based drugs are the front-line weapon in the treatment of human malaria cases, but there is concern that recent reports of slow clearing infections may signal developing resistance to treatment. In the absence of molecular markers for resistance, current efforts to monitor drug efficacy are based on the rate at which parasites are cleared from infections. However, some knowledge of the standing variation in parasite susceptibility is needed to identify a meaningful increase in infection half-life. Here, we show that five previously unexposed genotypes of the rodent malaria parasite Plasmodium chabaudi differ substantially in their in vivo response to treatment. Slower clearance rates were not linked to parasite virulence or growth rate, going against the suggestion that drug treatment will drive the evolution of virulence in this system. The level of variation observed here in a relatively small number of genotypes suggests existing ‘resistant’ parasites could be present in the population and therefore, increased parasite clearance rates could represent selection on pre-existing variation rather than de novo resistance events. This has implications for resistance monitoring as susceptibility may depend on evolved traits unrelated to drug exposure.

Glycoengineered factor IX variants with improved pharmacokinetics and subcutaneous efficacy

BACKGROUND

The rapid clearance of factor IX (FIX) necessitates frequent intravenous administration to achieve effective prophylaxis for patients with hemophilia B. Subcutaneous administration would be a preferred route of administration but is limited by bioavailability.

OBJECTIVES

To improve the pharmacokinetics (PK) and bioavailability of FIX, a screen was performed to identify positions for the introduction of novel glycosylation sites with maximal effect on PK and maintenance of coagulation activity.

METHODS

Two hundred fifty-one variants, each containing one additional N-linked glycosylation site, were screened in vitro, and the PK profiles of selected variants mapping to spatially distinct regions of FIX were evaluated in mice. Optimal variants were combined, and their PK and efficacy were determined in mice with hemophilia B.

RESULTS

Variants that mapped to spatially distinct regions of the FIX structure exhibited different degrees of improved PK and enabled selection of optimized sites while minimizing the loss of FIX activity. Combining the most effective N-glycan sites in the same FIX molecule resulted in further improvements in PK. An optimized variant containing three novel N-glycan sites (at amino acids 103, 151, and 228), and the activity enhancing 338A variant had double the specific activity of wild-type FIX, exhibited 4.5-fold reduced clearance and 2.4-fold increased subcutaneous bioavailability, and was efficacious at a fivefold lower mass dose than wild-type FIX after subcutaneous injection in a bleeding model in mice with hemophilia B.

CONCLUSIONS

Glycoengineering was used to significantly improve the subcutaneous PK and efficacy of FIX and may have advantages for subcutaneous dosing.

National survey of the management of eye emergencies in the accident and emergency departments by senior house officers: 10 years on--has anything changed?

OBJECTIVE

To assess changes in basic ophthalmic training of accident and emergency (A&E) senior house officers (SHOs) in the last 10 years, their own perceived level of confidence and the availability of appropriate equipment in their departments.

METHODS

A standardised structured questionnaire from a telephone survey carried out in 1993 was used. One SHO from each A&E department listed in the British Association of Emergency Medicine directory of 2003 was chosen at random and interviewed.

RESULTS

168 A&E departments were contacted and 133 SHOs were successfully interviewed (response rate 79.2%). The number of A&E departments with a slit lamp increased by 25.7% from 1993, and slit lamp training increased by 21%. There was no significant change in the prevalence of training in the management of eye emergencies (74.0% in 1993 vs 77.4% in 2003) and the proportion of SHOs who felt confident in dealing with these cases was unchanged.

CONCLUSIONS

A&E departments are better equipped with slit lamps 10 years on, and staff are being trained to use them. This has unfortunately not improved the confidence levels in dealing with eye emergencies, reflecting the lack of adequate basic ophthalmic training for A&E SHOs. Recent changes in postgraduate medical training could provide a platform to bring about the changes required.

Electrocardiographical case. Elderly man with acute breathlessness. Atrial tachycardia with variable AV conduction block and transient hyperkalaemia-induced aberrant conduction

A 67-year-old Chinese man presented to the emergency department with a history of abdominal bloating and shortness of breath. Initial electrocardiogram (ECG) showed atrial tachycardia (AT) with 2:1 atrioventricular (AV) conduction block. Six days after admission, he developed acute dyspnoea and confusion. Repeat ECG demonstrated a regular wide-complex tachycardia. Serum analysis revealed hyperkalaemia secondary to acute on chronic renal failure. Emergency treatment with intravenous calcium gluconate, 50% dextrose solution and short-acting insulin was instituted. The ECG promptly reverted to a narrow-complex AT with 2:1 AV conduction block. The diagnosis and treatment of AT are discussed.

Within-host competition in genetically diverse malaria infections: parasite virulence and competitive success

Humans and animals often become coinfected with pathogen strains that differ in virulence. The ensuing interaction between these strains can, in theory, be a major determinant of the direction of selection on virulence genes in pathogen populations. Many mathematical analyses of this assume that virulent pathogen lineages have a competitive advantage within coinfected hosts and thus predict that pathogens will evolve to become more virulent where genetically diverse infections are common. Although the implications of these studies are relevant to both fundamental biology and medical science, direct empirical tests for relationships between virulence and competitive ability are lacking. Here we use newly developed strain-specific real-time quantitative polymerase chain reaction protocols to determine the pairwise competitiveness of genetically divergent Plasmodium chabaudi clones that represent a wide range of innate virulences in their rodent host. We found that even against their background of widely varying genotypic and antigenic properties, virulent clones had a competitive advantage in the acute phase of mixed infections. The more virulent a clone was relative to its competitor, the less it suffered from competition. This result confirms our earlier work with parasite lines derived from a single clonal lineage by serial passage and supports the virulence-competitive ability assumption of many theoretical models. To the extent that our rodent model captures the essence of the natural history of malaria parasites, public health interventions which reduce the incidence of mixed malaria infections should have beneficial consequences by reducing the selection for high virulence.

Interactions of platelets, blood-borne tissue factor, and fibrin during arteriolar thrombus formation in vivo

Thrombus formation following vascular injury is an essential component of both hemostasis and pathologic vessel occlusion. This process occurs in a closed, pressurized environment in which blood flows rapidly over the injury site. Thrombus formation must occur quickly to reduce blood loss, but is carefully modulated to limit vessel occlusion. Circulating cells, plasma proteins, vessel wall components, and physical forces such as shear all influence thrombus formation. Historically, thrombus formation has been studied by isolating the separate components of blood involved in clot formation. With improved optical techniques, investigators have increasingly studied thrombus formation under conditions of flow in vitro and in live animals in vivo. Using multichannel fluorescence intravital videomicroscopy, the authors have studied the changes in the kinetics and deposition of platelets, fibrin, and tissue factor at the injury site during thrombosis in transgenic mice, bone marrow transplanted mice, and mice treated with pharmacological agents that modulate thrombosis. The differences in the kinetics of accumulation of the various components of thrombus in these mice have provided new insights about thrombus formation in arterioles. This review discusses the role of platelet intracellular signaling, P-selectin expression on platelets, and tissue factor-bearing microparticles in thrombus formation.

Fungal Pathogen Reduces Potential for Malaria Transmission

Using a rodent malaria model, we found that exposure to surfaces treated with fungal entomopathogens following an infectious blood meal reduced the number of mosquitoes able to transmit malaria by a factor of about 80. Fungal infection, achieved through contact with both solid surfaces and netting for durations well within the typical post-feed resting periods, was sufficient to cause >90% mortality. Daily mortality rates escalated dramatically around the time of sporozoite maturation, and infected mosquitoes showed reduced propensity to blood feed. Residual sprays of fungal biopesticides might replace or supplement chemical insecticides for malaria control, particularly in areas of high insecticide resistance.

Adrenal suppression from high-dose inhaled fluticasone propionate in children with asthma

This cross-sectional study was designed to examine the prevalence of adrenocortical suppression in children with asthma treated with high-dose inhaled fluticasone propionate (FP). Children and adolescents (n=50) with asthma, treated with inhaled FP at a dose of > or = 1,000 mg a day for > or = 6 months, were enrolled. Early morning serum cortisol was performed. Subjects with a serum cortisol of < 400 nmol x L(-1) had a tetracosactrin stimulation test. Fifty subjects of mean age 13.1 yrs were treated with a mean dose of 924.7 microg x m(-2) x day(-1) FP for a mean duration of 2 yrs. Of the 50 subjects, 36 (72%) had serum cortisol levels of < 400 nmol x L(-1) and underwent tetracosactrin stimulation test. Of these, 6 (17%) demonstrated a less than two-fold increase in serum cortisol from baseline and peak cortisol level of < or = 550 nmol x L(-1) at 30 or 60 min poststimulation. There was a significant negative correlation between the dose of FP x m(-2) and stimulated peak cortisol level. Biochemical evidence of adrenocortical insufficiency was demonstrated in 12% of the subjects, indicating that high-dose fluticasone propionate use may be associated with dose-dependent adrenocortical suppression.

Mannose-binding lectin (MBL) mutants are susceptible to matrix metalloproteinase proteolysis: potential role in human MBL deficiency

Mannose-binding lectin (MBL) plays a critical role in innate immunity. Point mutations in the collagen-like domain (R32C, G34D, or G37E) of MBL cause a serum deficiency, predisposing patients to infections and diseases such as rheumatoid arthritis. We examined whether MBL mutants show enhanced susceptibility to proteolysis by matrix metalloproteinases (MMPs), which are important mediators in inflammatory tissue destruction. Human and rat MBL were resistant to proteolysis in the native state but were cleaved selectively within the collagen-like domain by multiple MMPs after heat denaturation. In contrast, rat MBL with mutations homologous to those of the human variants (R23C, G25D, or G28E) was cleaved efficiently without denaturation in the collagen-like domain by MMP-2 and MMP-9 (gelatinases A and B) and MMP-14 (membrane type-1 MMP), as well as by MMP-1 (collagenase-1), MMP-8 (neutrophil collagenase), MMP-3 (stromelysin-1), neutrophil elastase, and bacterial collagenase. Sites and order of cleavage of the rat MBL mutants for MMP-2 and MMP-9 were: Gly(45)-Lys(46) --> Gly(51)-Ser(52) --> Gly(63)-Gln(64) --> Asn(80)-Met(81) which differed from that of MMP-14, Gly(39)-Leu(40) --> Asn(80)-Met(81), revealing that the MMPs were not functionally interchangeable. These sites were homologous to those cleaved in denatured human MBL. Hence, perturbation of the collagen-like structure of MBL by natural mutations or by denaturation renders MBL susceptible to MMP cleavage. MMPs are likely to contribute to MBL deficiency in individuals with variant alleles and may also be involved in clearance of MBL and modulation of the host response in normal individuals.

Possible protective role of HLA-B*2706 for ankylosing spondylitis

HLA-B27 is strongly associated with ankylosing spondylitis (AS) but the role of the HLA molecule itself is still unclear. In this study on Singapore Chinese, we have subtyped 50 B27 positive AS patients and 45 B27 positive normals and found that the B*2706 allele has a significant negative association with disease (p = 0.047). Together with recent data indicating the existence of AS "protective" B27 alleles, our data shows that the HLA molecule itself plays a crucial role in disease development.

Lipids and lipoproteins during antihypertensive drug therapy. Comparison of doxazosin and atenolol in a randomized, double-blind trial: the Alpha Beta Canada Study

A randomized double-blind trial comparing the alpha-adrenergic blocker doxazosin and the beta-adrenergic blocker atenolol was completed by 131 patients with mild to moderate hypertension. Blood pressure and fasting blood lipids were determined at baseline and 4, 12, and 24 weeks of treatment. At entry, plasma lipids and lipoproteins were similar in those patients randomized to doxazosin or atenolol. After 24 weeks of treatment with atenolol, there were significant (P < .05) decreases in high-density lipoprotein cholesterol (HDL-C) and increases in triglycerides and very-low-density triglycerides (VLDL-T). In contrast, doxazosin was associated with significant (P < .05) increases in HDL-C and decreases in triglycerides and VLDL-T. There were no significant differences in HDL apolipoprotein (apo) A-I or low-density lipoprotein apoB between the drugs, but atenolol decreased the ratio of HDL-C to apoA-I, and doxazosin increased this ratio, differences that were statistically significant (P < .002). Neither apoA-I nor apoB concentration at baseline nor apoE phenotype was predictive of the lipid responses during antihypertensive treatment with either drug. Thus, there are significant favorable changes in HDL-C, total triglycerides, and VLDL-T between patients with mild to moderate hypertension and normal plasma lipids when treated with the alpha-blocker doxazosin compared with the beta-blocker atenolol. Plasma lipid or apo concentrations were not predictive of their lipid response during antihypertensive therapy with either of these agents.

Comparative trial of doxazosin and atenolol on cardiovascular risk reduction in systemic hypertension. The Alpha Beta Canada Trial Group

The impact of treating hypertension on coronary artery disease has been less than anticipated from epidemiologic studies of cardiovascular risk factors. It has been suggested that adverse effects on lipids of traditional diuretic or beta-blocker regimens may diminish the potential benefits of antihypertensive therapy. Patients with mild to moderate systemic hypertension and normal serum lipids (n = 191) were randomly assigned to doxazosin or atenolol. After dose titration to goal diastolic blood pressure of < or = 90 mm Hg, patients continued treatment for a further 24 weeks. The principal outcome measurement was overall coronary artery disease risk using the Framingham formula. Relative risk of coronary artery disease was reduced to 92.4% of baseline (p = 0.144) for evaluable patients taking atenolol (n = 71), and to 74.6% (p = 0.0001) for patients taking doxazosin (n = 51): atenolol versus doxazosin, p = 0.0074. In patients who met the strict Framingham criteria for age, total cholesterol and high density lipoprotein cholesterol, the relative risk of coronary artery disease for patients taking atenolol (n = 23) was reduced to 86.2% of baseline (p = 0.082), and to 67.4% (p = 0.0004) for patients taking doxazosin (n = 18): atenolol versus doxazosin, p = 0.049. Alpha blockade with doxazosin was more effective than beta blockade with atenolol in reducing the risk of coronary artery disease in hypertensive patients because of the beneficial effects of doxazosin on high-density lipoprotein cholesterol. Overall withdrawal rate was greater in the alpha-blocker group because of a lower response rate and more adverse events.

Evaluation of biophysical fetal assessment in high-risk pregnancy to assess ultrasound parameters suitable for screening in the low-risk population

During a 1-year period, 662 pregnant women at 24-43 weeks' gestation were referred to the Department of Obstetrics and Gynaecology, at the Queens University Belfast, for fetal assessment because they were clinically suspected to be at high risk of perinatal complications. The results of our investigations were made available to the referring obstetricians who undertook the further management of the pregnancies. Subsequently six pregnancies resulted in perinatal deaths and 97 (14.7%) in the delivery of small-for-gestational-age infants. We restrospectively analyzed the data from ultrasonographic evaluation of the fetus and subjective and objective assessments of the amniotic fluid volume to determine their value in the prediction of adverse perinatal outcome. A fetal abdominal circumference < 10th centile for gestation or a subjectively reduced amniotic fluid volume identified 87 (90%) of small-for-gestational-age infants and five of the six perinatal deaths. When comparing the abdominal circumference and subjective liquor volume, both were sensitive in predicting delivery of a small-for-gestational-age fetus (sensitivity 86% vs. 53%, respectively) and perinatal death (sensitivity 50% vs. 83%, respectively). We suggest that, since assessments of these two factors are complementary in evaluating a high-risk pregnancy and can be measured in under 5 min, they now warrant consideration for screening in a prospective randomized trial in an unselected low-risk population.

Early amniocentesis: experience of 222 consecutive patients, 1987-1988

Early amniocentesis from 9 to 14 weeks' gestation provides a safe and accurate method of prenatal diagnosis of cytogenetic and biochemical disorders. There was a 100 per cent success rate in culturing the amniotic cells from 222 samples obtained between 9 and 14 weeks' gestation. Follow-up of the patients to delivery revealed an abortion rate of 1.4 per cent. Among the 207 live- and stillborn infants, only one had a congenital abnormality (bilateral talipes equino-varus) and no infant had respiratory distress syndrome or pneumonia. Eleven pregnancies were terminated following the detection of a chromosomal, biochemical, or congenital abnormality (5.0 per cent). However, before the procedure of early amniocentesis becomes routine clinical practice, it requires appraisal by a randomized clinical trial.

Interstitial parametrial implants in carcinoma of the cervix stage II-B

This retrospective analysis has been undertaken to ascertain whether an improvement in results can be obtained in Stage II-B cervical carcinoma with the use of interstitial parametrial irradiation. Between September 1972 and March 1982, 43 patients were treated by conventional intracavitary irradiation. Nine patients at high risk for local recurrence underwent post-radiation hysterectomy. Since 1980, 45 patients were entered into a study using parametrial interstitial implants and no hysterectomy. Patients were not allocated randomly and the interstitial group contained a disproportionate number of patients with poor prognostic features. Mean follow-up for the conventional radiotherapy group was 80 months, and for the interstitial group was 42 months. Overall pelvic control and actuarial survival in the conventional radiotherapy group (84 and 75%, respectively) were similar (log rank p-value = .61) to that observed in the interstitial implant group (80 and 77%). Analysis of pelvic control rates showed no significant advantage for either treatment group when compared by the various prognostic factors. The frequency of complications, however, was significantly higher in the interstitially irradiated patients (21% vs. 7%, p = .044).