Design of an adaptive randomized clinical trial of intravenous citrulline for sickle cell pain crisis in the emergency department

Background

Vaso-occlusive pain crisis (VOC) is the most frequent cause for Emergency Department (ED) visits and hospital admissions for patients with sickle cell disease (SCD). Nitric oxide plays a critical role in the pathogenesis of vaso-occlusion. The amino acid, citrulline, is the main endothelial nitric oxide booster that offers the potential to ameliorate vaso-occlusion and decrease the risk of hospitalization.

Objective

In this two-part study, the goal of the first part is to determine the pharmacokinetic profile of intravenous (IV) l-citrulline and optimal dose for the second part of the study, which is to determine the efficacy and tolerability of the intervention in patients with SCD.

Design

A phase I/IIA open-label dose-finding study with subsequent double-blind, placebo-controlled, randomized Study of l-citrulline in children and adolescents with SCD presenting to the ED in VOC.

Methods

Part 1: Subjects experiencing VOC are enrolled in an open-label, ascending dose of IV l-citrulline to identify the optimum dose with endpoints of pharmacokinetic parameters, pain scores, reduction of opioid use, quality of life, proportion admitted to the hospital for treatment of pain, readmission rates, and assessment of adverse events. Part 2 of the trial is a double-blind, placebo-controlled adaptive "pick-the-winner" design to evaluate the efficacy and tolerability of IV l-citrulline in patients with SCD while receiving standard of care therapy for VOC.

Summary

This ED based sickle cell adaptive trial will determine the optimal dose for IV citrulline and whether the intervention improves outcome as a potential novel therapy for VOC in SCD.

POS1163 PHARMACOKINETICS OF PEGLOTICASE AND METHOTREXATE POLYGLUTAMATE(S) IN PATIENTS WITH UNCONTROLLED GOUT RECEIVING PEGLOTICASE AND CO-TREATMENT WITH METHOTREXATE

Background

In a prior open-label, single-arm trial in adults with uncontrolled gout (MIRROR open-label [OL] trial), methotrexate (MTX) co-treatment with pegloticase suggested improved efficacy of pegloticase by reducing its immunogenicity.1,2 The current randomized, controlled trial (MIRROR RCT) confirmed that pegloticase-MTX co-therapy markedly increased pegloticase response rate (response defined as serum uric acid <6 mg/dL during ≥80% of Month 6) compared to pegloticase-placebo (PBO) co-therapy (71.0% vs. 38.5%) with a decreased infusion reaction rate and no new safety signals reported.

Objectives

To evaluate systemic exposures of pegloticase and its immunogenicity in uncontrolled gout patients receiving pegloticase with and without MTX as part of the MIRROR RCT; and to determine exposure of methotrexate polyglutamate(s) (MTX-PGs) in uncontrolled gout patients through Month 6 of treatment.

Methods

In MIRROR RCT, MTX (15 mg/wk) or matching PBO was given orally 4 weeks prior to the first pegloticase dose and continued weekly, in combination with pegloticase 8 mg given intravenously every 2 weeks, over a 52-week treatment period. Pre-infusion blood samples were collected to measure MTX polyglutamates (MTX-PGs, including MTX-PG1-5) in red blood cells and pre- and post-infusion serum samples were obtained to measure trough (Cmin) and peak (Cmax) concentrations of pegloticase, respectively, at multiple visits. MTX-PG and pegloticase concentrations were summarized by visit and by treatment group. Pre-infusion serum samples for anti-polyethylene glycol (PEG) antibody (Ab) measurement were also collected at multiple pre-defined time points. Anti-PEG Ab incidence and titer were summarized by visit and by treatment group.

Results

Overall, higher Cmax and Cmin of pegloticase were observed in the pegloticase + MTX group than in the pegloticase + PBO group (Figure 1). At Week 14, median (first quartile [Q1], third quartile [Q3]) Cmin was 1.32 (0.73, 1.74) µg/mL and 0.63 (0.30, 1.28) µg/mL for the pegloticase + MTX and pegloticase + PBO groups, respectively. Median (Q1, Q3) Cmax was 3.01 (1.94, 3.94) µg/mL and 2.66 (1.45, 3.20) µg/mL for the pegloticase + MTX and pegloticase + PBO groups, respectively. Improved pegloticase response was associated with higher pegloticase concentrations. At Week 14, Cmin was below the quantitation limit (0.6 µg/mL) for 8 of 10 non-responders and 1.26 (0.72, 1.71) µg/mL for responders. MTX co-administration reduced the incidence of new anti-PEG antibody formation. The proportion of subjects with an increase from baseline in anti-PEG Ab titers or who were negative at baseline and developed an anti-PEG Ab response at ≥1 post-dose time point during pegloticase treatment was 29.5% and 51.0%, for the pegloticase + MTX and pegloticase + PBO groups, respectively. The pegloticase + MTX group had overall lower titer levels than those in the pegloticase + PBO group. Positive anti-PEG Ab status was associated with a lower pegloticase Cmin. Concentrations of MTX-PGs were maintained during the treatment course in the pegloticase + MTX group, suggesting compliance with MTX administration. There was no apparent difference in concentrations of MTX-PGs (including MTX-PG3, the predominant form of MTX-PGs4) between responders and non-responders. MTX-PG concentrations were in the same range as those reported for low-dose oral MTX use in patients with rheumatoid arthritis,3 suggesting no impact of pegloticase on MTX PK.

Conclusion

Pegloticase 8 mg IV every 2 weeks with MTX co-treatment (oral 15 mg weekly) reduced anti-PEG Ab incidence and resulted in higher pegloticase exposures compared to pegloticase administered with PBO, consistent with the increased clinical efficacy observed with pegloticase + MTX co-administration.

References

[1]Botson J, et al. J Rheumatol 2021;48:767-74

[2]Song Y, et al. Arthritis Rheum 2020;72(suppl 10)

[3]Dervieux T, et al. Ann Rheum Dis 2013;72:908-10

[4]Choi R. J Pharm Biomed Anal 2021;201:114124

Disclosure of Interests

Yan Xin Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics, Yang Song Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics, Michael E. Weinblatt Consultant of: Horizon Therapeutics, Jason Chamberlain Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics, Jennifer Zarzoso Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics, Katie Obermeyer Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics, Stephen Sainati Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics, Colleen Canavan Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics, Srini Ramanathan Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics

POS1136 PHARMACOKINETICS OF PEGLOTICASE AND METHOTREXATE POLYGLUTAMATE(S) IN PATIENTS WITH UNCONTROLLED GOUT RECEIVING PEGLOTICASE AND CO-TREATMENT OF METHOTREXATE

Background:

In an open-label, single-arm trial in adult patients with uncontrolled gout (MIRROR open-label [OL] trial) evaluating pegloticase co-treatment with methotrexate (MTX); 78.6% patients were responders, defined as maintenance of serum uric acid <6 mg/dL for at least 80% of the time during month 6 [weeks 20, 22, and 24]. In comparison, 42% patients achieved a response during month 3 and 6 in historical Phase 3 monotherapy trials of pegloticase (C0405 and C0406)1. MTX co-treatment is shown to improve the pharmacokinetics (PK) of biologics by attenuating the formation of anti-drug antibodies2.

Objectives:

To determine the systemic exposures of pegloticase and methotrexate polyglutamate(s) (MTX-PGs) in uncontrolled gout patients receiving pegloticase and MTX; to evaluate the effect of MTX on the PK of pegloticase in comparison to historical pegloticase monotherapy trials (C0405 and C0406)3, 4; and to evaluate the immunogenicity of pegloticase in co-treatment with MTX.

Methods:

In the MIRROR OL trial, MTX (15 mg/week) was given orally 4 weeks prior to the first pegloticase dose and continued weekly, in combination with pegloticase 8 mg given intravenously every 2 weeks, for a treatment duration of up to 52 weeks. Pre-infusion samples were collected to measure MTX-PGs in red blood cells. Pre- and post-infusion blood samples were obtained to measure the peak (Cmax) and trough (Cmin) concentrations of pegloticase at multiple visits. Anti-drug antibody blood samples were collected at multiple visits. The impact of MTX on pegloticase PK was evaluated by comparing pegloticase exposures with MTX from this trial to historical monotherapy data (C0405 and C0406)3, 4. The observed pegloticase concentrations with MTX were also overlaid with the 90% prediction interval based on the population PK model5 from C0405 and C0406.

Results:

Pegloticase and MTX-PG levels were determined in 14 patients. The 11 responders were generally associated with higher pegloticase exposures than the non-responders, especially Cmin (Figure 1). Concomitant treatment of MTX resulted in fewer patients with Cmin below quantitation limit (BQL) (5/14 [36%] with MTX vs 63/82 [77%] without MTX), and higher overall Cmin (median: 1.03 µg/ml with MTX vs BQL without MTX); Cmax was slightly higher (median [Q1, Q3]: 2.11 [1.65, 2.59] µg/mL with MTX vs 1.51 [BQL, 2.48] µg/mL without MTX). Pegloticase co-treatment with MTX resulted in more concentrations above the predicted median value of pegloticase, compared to monotherapy. ADA data is consistent with pegloticase PK and efficacy. Significant increase in ADA titers were only observed in 2 subjects (both were non-responders) at time corresponding to the loss of pegloticase exposure and increases in sUA levels. Concentrations of MTX-PGs were maintained during the treatment course, suggesting compliance of MTX administration. There was no apparent difference in concentrations of MTX-PGs between responders and non-responders.

Conclusion:

Pegloticase 8 mg IV every 2 weeks co-treatment with MTX 15 mg weekly resulted in fewer patients with pegloticase Cmin below the quantification limit (BQL) and gave higher overall trough concentrations (Cmin) compared to pegloticase monotherapy in the phase 3 studies.

Pegloticase 8 mg IV every 2 weeks co-treatment with MTX 15 mg weekly was associated with an improved response rate for pegloticase in association with improved drug levels in these patients with uncontrolled gout compared to pegloticase monotherapy in the phase 3 studies.

References:

[1]Botson J., et al. J Rheumatol. 2020; doi: 10.3899/jrheum.200460

[2]Goss S. L., et al. Clin Ther;2018, 40 (2).

[3]Lipsky P. E., et al. Arthritis Res Ther;2014, 16 (2).

[4]Sundy J. S., et al. JAMA;2011, 306 (7).

[5]Yue C. S., et al. ASCPT, Atlanta, 2010.

Disclosure of Interests:

Yang Song Shareholder of: Horizon Therapeutics plc, Employee of: Horizon Therapeutics plc, Yan Xin Shareholder of: Horizon Therapeutics plc, Employee of: Horizon Therapeutics plc, Michael E. Weinblatt Shareholder of: Canfite, Inmedix, Lycera, Vorso, Scipher, Grant/research support from: Crescendo Bioscience, Bristol Myers Squibb, Sanofi, Eli Lilly, Amgen, Jason Chamberlain Shareholder of: Horizon Therapeutics plc, Employee of: Horizon Therapeutics plc, Katie Obermeyer Shareholder of: Horizon Therapeutics plc, Employee of: Horizon Therapeutics plc, Lin Zhao Shareholder of: Horizon Therapeutics plc, Employee of: Horizon Therapeutics plc, Colleen Canavan Shareholder of: Horizon Therapeutics plc, Employee of: Horizon Therapeutics plc, Paul M. Peloso Shareholder of: Horizon Therapeutics plc, Employee of: Horizon Therapeutics plc, Srini Ramanathan Shareholder of: Horizon Therapeutics plc, Employee of: Horizon Therapeutics plc.

Effectiveness of progesterone, cerclage and pessary for preventing preterm birth in singleton pregnancies: a systematic review and network meta-analysis

BACKGROUND

Preterm birth (PTB) is the leading cause of infant death, but it is unclear which intervention is best to prevent it.

OBJECTIVES

To compare progesterone, cerclage and pessary, determine their relative effects and rank them.

SEARCH STRATEGY

We searched Medline, EMBASE, CINAHL, Cochrane CENTRAL and Web of Science (to April 2016), without restrictions, and screened references of previous reviews.

SELECTION CRITERIA

We included randomised trials of progesterone, cerclage or pessary for preventing PTB in women with singleton pregnancies at risk as defined by each study.

DATA COLLECTION AND ANALYSIS

We extracted data by duplicate using a piloted form and performed Bayesian random-effects network meta-analyses and pairwise meta-analyses. We rated evidence quality using GRADE, ranked interventions using SUCRA and calculated numbers needed to treat (NNT).

MAIN RESULTS

We included 36 trials (9425 women; 25 low risk of bias trials). Progesterone ranked first or second for most outcomes, reducing PTB < 34 weeks [odds ratio (OR) 0.44; 95% credible interval (CrI) 0.22-0.79; NNT 9; low quality], <37 weeks (OR 0.58; 95% CrI 0.41-0.79; NNT 9; moderate quality), and neonatal death (OR 0.50; 95% CrI 0.28-0.85; NNT 35; high quality), compared with control, in women overall at risk. We found similar results in the subgroup with previous PTB, but only a reduction of PTB < 34 weeks in women with a short cervix. Pessary showed inconsistent benefit and cerclage did not reduce PTB < 37 or <34 weeks.

CONCLUSIONS

Progesterone was the best intervention for preventing PTB in singleton pregnancies at risk, reducing PTB < 34 weeks, <37 weeks, neonatal demise and other sequelae.

TWEETABLE ABSTRACT

Progesterone was better than cerclage and pessary to prevent preterm birth, neonatal death and more in network meta-analysis.

Seasonality of suicide behavior in Northwest Alaska: 1990-2009

OBJECTIVES

Suicide is a leading cause of death worldwide, and disproportionately affects Indigenous populations. Seasonal suicide patterns are variable in the literature, and could offer novel approaches to the timing and focus of prevention efforts if better understood. With a suicide surveillance system in place since 1989, this study offers an unprecedented opportunity to explore seasonal variations in both fatal and non-fatal suicide behavior in an Indigenous Arctic region.

STUDY DESIGN

Cross-sectional.

METHODS

In this descriptive study, we analyzed data collected from 1990 to 2009 in the rural northwest region of Alaska, both graphically and using the chi-squared test for multinomials.

RESULTS

We found a significant monthly variation for suicide attempts, with a peak in suicide behavior observed between April and August (P = 0.0002). Monthly variation was more pronounced among individuals ≤29 years of age, and was present in both males and females, although the seasonal pattern differed by sex.

CONCLUSIONS

Our findings of a significant seasonal pattern in suicide behavior, with monthly variation (summer peak) in non-fatal suicide behavior among younger age groups, and among both males and females can assist planners in targeting subpopulations for prevention at different times of the year.

Sequencing and phylogenetic characterisation of a fatal Crimean - Congo haemorrhagic fever case imported into the United Kingdom, October 2012

A patient with fever, and haemorrhagic symptoms was admitted to a hospital in Glasgow on 2 October 2012. Since he had returned from Afghanistan, serum samples were sent for diagnosis at the Rare and Imported Pathogens Laboratory, where a real-time reverse transcriptase-PCR diagnosis of Crimean – Congo haemorrhagic fever was made within 3 hrs after receipt of the sample. Hereafter the patient was transferred to a high-security infectious diseases unit in London but died on 6 October.

Sequencing and phylogenetic characterisation of a fatal Crimean – Congo haemorrhagic fever case imported into the United Kingdom, October 2012

Binary file ES_Abstracts_Final_ECDC.txt matches

Platelet P2Y(12) receptor influences the vessel wall response to arterial injury and thrombosis

BACKGROUND

Platelets are believed to play an important role in atherogenesis and the vessel response to vascular injury. The P2Y(12) receptor (P2Y(12)) plays a central role in amplifying platelet aggregation, dense granule and alpha-granule secretion, P-selectin expression, microparticle formation, and procoagulant membrane changes, regardless of the activating stimulus. We hypothesized that P2Y(12) deficiency might reduce the vessel wall response to vascular injury as well as thrombosis in murine vascular injury models.

METHODS AND RESULTS

P2Y(12)-deficient (-/-) mice and littermate controls (+/+) were bred on a C57 BL/6 background. In vivo murine models of arterial injury were employed alone and in combination with bone marrow transplantation to investigate the role of P2Y(12) in the vessel wall response to arterial injury and thrombosis. At 21 days after ferric chloride injury, neointima formation in P2Y(12)(-/-) arteries was significantly less than that observed in control strain arteries (P<0.025). In agreement with this, the intima-media ratio was significantly greater in femoral wire-injured arteries from P2Y(12)(+/+) compared with P2Y(12)(-/-) animals (P<0.05). Bone marrow transplantation was used to examine the importance of vessel wall P2Y(12) versus platelet P2Y(12). Analysis of arterial sections from chimeric animals at 21 days after injury revealed a smaller intima-media ratio in -/- to +/+ animals than in the positive (+/+ to +/+) control group (P<0.01).

CONCLUSIONS

These data demonstrate a role for platelet P2Y(12) in the vessel wall response to arterial injury and thrombosis. This illustrates the manner in which platelets may contribute to atherogenesis and restenosis.

Women's perception of self-worth and access to health care

OBJECTIVE

: Research has shown differences in health status and health care utilization related to culture, economic status, and health care development. This paper reports on a study comparing attitudes of women in three countries, at various stages of development, about their own health and self-worth and asks if these differences account for differences in health care utilization and inequities in health status.

METHOD

: A questionnaire, administered to 100 women in each of Yemen, Uganda and Canada, explored women's perception of their own health and health care seeking behavior.

RESULT

: Women's perception of themselves as worthy of care was positively related to utilization. The ability to make one's own health care decisions varied with her country's development level. Implementation strategies must consider women's decision-making capacity.

CONCLUSION

: To achieve improved health status, policies and programs must commit to encouraging appropriate social and cultural changes, using a 'cross-sectoral approach', involving both gender and development issues.

Crimean-Congo haemorrhagic fever virus: sequence analysis of the small RNA segments from a collection of viruses world wide

Crimean-Congo haemorrhagic fever virus (CCHFv) is a member of the genus Nairovirus in the family Bunyaviridae. It possesses a tripartite, single stranded RNA genome of negative polarity consisting of large (L), medium (M) and small (S) segments. CCHF virus is enzootic in life stock and wild animals in many parts of the Middle East, Asia and Africa and is also recognised in Southeast Europe. Severe disease, manifest as haemorrhagic fever and high mortality rates (up to 50%), is only recognised in humans. We have determined the complete sequence of the small genomic RNA segment from several strains of CCHF virus from outbreaks in Pakistan 2000, Baghdad 1976 and Uzbekistan 1967. Phylogenetic analysis of three datasets of sequences from the small genomic RNA segment available from a range of strains indicates that they can be divided into seven subtypes. Superimposed on this pattern are links between distant geographic locations, pointing to the existence of a global reservoir of CCHFv. In some cases these links may originate from trade in livestock, and long-distance carriage of virus or infected ticks during bird migration.

The role of professional associations in reducing maternal mortality worldwide

The death of hundreds of thousands of women due to pregnancy-related complications casts a shadow over the modern obstetrical world. This paper examines the potential roles and responsibilities of professional obstetrical and midwifery associations in addressing this tolerated tragedy of maternal deaths. We examine the successes and challenges of obstetrical and midwifery associations and encourage the growth and development of active associations to address maternal mortality within their own borders. Professional associations can play a vital role in the reduction of maternal mortality worldwide. Their roles include lobbying for women's health and rights, setting standards of practice, raising awareness and team building. Associations from developed countries can influence and strengthen their colleagues within developing countries; for example, the FIGO Save the Mothers initiative. Professional associations should be encouraged to play an active role in reducing maternal mortality within their own country and abroad.

Stable expression of calpain 3 from a muscle transgene in vivo: immature muscle in transgenic mice suggests a role for calpain 3 in muscle maturation

Limb-girdle muscular dystrophy, type 2A (LGMD 2A), is an autosomal recessive disorder that causes late-onset muscle-wasting, and is due to mutations in the muscle-specific protease calpain 3 (C3). Although LGMD 2A would be a feasible candidate for gene therapy, the reported instability of C3 in vitro raised questions about the potential of obtaining a stable, high-level expression of C3 from a transgene in vivo. We have generated transgenic (Tg) mice with muscle-specific overexpression of full-length C3 or C3 isoforms, which arise from alternative splicing, to test whether stable expression of C3 transgenes could occur in vivo. Unexpectedly, we found that full-length C3 can be overexpressed at high levels in vivo, without toxicity. In addition, we found that Tg expressing C3 lacking exon 6, an isoform expressed embryonically, have muscles that resemble regenerating or developing muscle. Tg expressing C3 lacking exon 15 shared this morphology in the soleus, but not other muscles. Assays of inflammation or muscle membrane damage indicated that the Tg muscles were not degenerative, suggesting that the immature muscle resulted from a developmental block rather than degeneration and regeneration. These studies show that C3 can be expressed stably in vivo from a transgene, and indicate that alternatively spliced C3 isoforms should not be used in gene-therapy applications because they impair proper muscle development.

Transforming growth factor-beta: a promising target for anti-stenosis therapy

Transforming growth factor-beta (TGF-beta) is the general name for a family of cytokines which have widespread effects on many aspects of growth and development. The TGF-beta isoforms are produced by most cell types and exert a wide range of effects in a context-dependent autocrine, paracrine or endocrine fashion via interactions with distinct receptors on the cell surface. TGF-beta is involved in the wound healing process and, thus plays a significant role in the formation of a restenotic lesion after percutaneous transluminal coronary angioplasty (PTCA) or stenting. Perhaps because of its wide-ranging effects, TGF-beta is usually released from cells in a latent form, and its activation and signaling are complex. Manipulation of the TGF-beta1, TGF-beta2, and TGF-beta3 isoforms by inhibiting their expression, activation, or signaling reduces scarring and fibrosis in animal models. However, to date, few have reached clinical trial. This review summarizes current knowledge on the activation and signaling of TGF-beta, and focuses on the anti-TGF-beta strategies which may lead to clinical applications in the prevention of restenosis following PTCA or stenting.

Improvement of forage production in Calliandra calothyrsus: methodology for the identification of an effective inoculum containing Rhizobium strains and arbuscular mycorrhizal isolates

The overall aim of this paper is to describe the selection of effective rhizobia and arbuscular mycorrhizas (AM), which after inoculation, will significantly improve the forage production of Calliandra calothyrsus under field conditions. To achieve this objective, the following activities were carried out: (i) establishment from both nodules and soil samples of a collection of microsymbionts (rhizobium and AM) of C. calothyrsus from Central America (Mexico, Honduras, Guatemala, Nicaragua and Costa Rica), also from outside its native range in Cameroon, Kenya and New Caledonia; (ii) identification under glasshouse conditions of the most effective rhizobia and AM isolates; (iii) production of a solid selected inoculum for field trials; (iv) examination of the impact of the inoculation on the growth of C. calothyrsus monitored under nursery conditions. We have screened 446 rhizobia strains in the nursery and identified six as being very effective at nodulating the host plant. They originated from Costa Rica (CCCR15 and CCCR1), from New Caledonia (CCNC26), from Cameroon (CCC22) and from Kenya (KWN35 and KCC6). In relation to AM, five isolates have been selected for the ability to infect and promote growth of the host plant--two isolates of Gigaspora albida isolated from Kenya (GA1b and GA2); one isolate of Scutellospora verrucosa isolated from Kenya (SV2c); one isolate of Scutellospora calospora isolated from Guatemala (SC2) and one isolate of Glomus etunicatum isolated from Honduras (GE1). Further experiments will test these selected inocula, singly and in mixtures, in order to obtain an inoculant which significantly improves the growth of C. calothyrsus and to enable its distribution to farmers who use this woody legume for forage production on their farms.

TGFbeta is active, and correlates with activators of TGFbeta, following porcine coronary angioplasty

OBJECTIVE

Restenosis following angioplasty involves processes that may be influenced by local production of cytokines. We investigated the expression of active and total transforming growth factor beta (TGFbeta) following porcine coronary angioplasty (PTCA), and have correlated this with the expression of potential in vivo activators of TGFbeta: mannose-6-phosphate/insulin-like growth factor-II (M6P/IGF-II) receptor and thrombospondin-1.

METHODS

Oversized porcine PTCA was performed and the arteries excised after selected intervals. Levels of in situ active and total (active plus latent) TGFbeta were determined using a modified plasminogen activator-inhibitor/luciferase bioassay.

RESULTS

Levels of active TGFbeta significantly increased 2 h to 7 days after angioplasty, compared to non-injured controls. Levels returned to baseline by 28 days. Active TGFbeta in tissues adjacent to the injured artery did not change. Total TGFbeta was significantly higher than controls 2-6 h after injury. M6P/IGF-II receptor mRNA was upregulated between 6 h and 3 days after injury, with protein detectable at 3-28 days. Thrombospondin-1 was detected between 1 h and 14 days.

CONCLUSIONS

We conclude that balloon injury causes an early rapid increase in levels of active TGFbeta, that correlates with the expression of TGFbeta activators. Thus, TGFbeta is a good potential target for anti-restenotic therapies.

Capsid protein diversity among Norwalk-like viruses

We have determined the complete capsid gene sequence of 20 Norwalk-like viruses (NLVs) collected predominantly from outbreaks in the UK between 1989 and 1996. These comprised nine genogroup I and eleven genogroup II strains. Phylogenetic analysis of these and 15 published sequences suggest seven genomic sub-groups within genogroup I, including three previously described. In genogroup II, eight sub-groups were apparent, of which four were novel. Amino acid identities between strains of distinct genogroups ranged from 37 to 44% while varying between 61 and 100% for strains within a genogroup. Separate phylogenetic analyses of the N-terminus and central variable region of the capsid showed good correlation. Sequence divergence between strains was greatest within the central variable region, with amino acid sequence identities as low as 28% within a genogroup. These 15 genomic sub-groups provide a framework for further investigations of genetic and antigenic relationships within this calicivirus clade.

Effect of selective or combined inhibition of integrins alpha(IIb)beta(3) and alpha(v)beta(3) on thrombosis and neointima after oversized porcine coronary angioplasty

BACKGROUND

Thrombosis and neointima formation limit the efficacy of coronary angioplasty (PTCA). Clinical trials have implicated the adhesion molecules integrin alpha(IIb)beta(3) and integrin alpha(v)beta(3) in these processes. The roles of these molecules in vascular smooth muscle cell adhesion, platelet aggregation, and the thrombotic and neointimal response to oversize porcine PTCA was investigated by use of a selective alpha(IIb)beta(3) antagonist (lamifiban), a selective alpha(v)beta(3) antagonist (VO514), and a combined alpha(IIb)beta(3)/alpha(v)beta(3) antagonist (G3580).

METHODS AND RESULTS

In vitro, both alpha(v)beta(3) inhibitors caused dose-dependent inhibition of porcine vascular smooth muscle cell adhesion to vitronectin but not to collagen type IV, fibronectin, or laminin, whereas selective alpha(IIb)beta(3) inhibition had no effect. Intravenous infusions of either alpha(IIb)beta(3) inhibitor in swine profoundly inhibited ex vivo platelet aggregation to ADP, whereas selective alpha(v)beta(3) inhibition had no effect. In a porcine PTCA model, intravenous infusions of the integrin antagonists were administered for 14 days after oversized balloon angioplasty injury. After PTCA, there was regional upregulation of integrin alpha(v)beta(3) in the developing neointima, as assessed by immunohistochemistry. Six hours after PTCA, obstruction of lumen by thrombus was reduced significantly by alpha(IIb)beta(3) inhibition compared with either control or alpha(v)beta(3) inhibition (mean control, 18.7%; VO514, 18.5%; lamifiban, 6.4%; G3580, 7.9%). Twenty-eight days after PTCA, there was a significant reduction of neointima with inhibitors of either integrin (mean intima/media ratio: control, 3.08; VO514, 1.33; lamifiban, 0.97; G3580, 1.32).

CONCLUSIONS

We conclude that both integrin alpha(IIb)beta(3) and integrin alpha(v)beta(3) participate in neointima development after experimental angioplasty.

99TCm-labeled leucocyte scan for detecting infection of vascular graft involving groin

The clinical value of Technitium-99TCm leucocyte in detecting early post-operative infection of prosthetic vascular grafts, to and from the femoral artery involving groin dissection is assessed. Twenty-five patients underwent bypass procedure using either Dacron or PTFE grafts. 99TCm labeled leucocyte scans were undertaken between 6-8 days following the bypass procedure. Fourteen patients had normal scans and no subsequent evidence of graft infection. The remaining 11 patients had abnormal scans discharge. These patients underwent serial scanning until the scan normalised or graft infection developed. Of 11 patients, who had abnormal initial scans, 2 developed clinical groin infection and were thus true positive, 7 patients subsequently had normal scans, 2 patients died of other causes. The sensitivity of 99TCm labeled leucocyte scan is 100%, but unlike some previous reports, we found a low specificity. The graft material used did not make any difference as far as the sensitivity or specificity of detection of graft infection was concerned.

Evidence for an RNA-based catalytic mechanism in eukaryotic nuclear ribonuclease P

Ribonuclease P is the enzyme responsible for removing the 5'-leader segment of precursor transfer RNAs in all organisms. All eukaryotic nuclear RNase Ps are ribonucleoproteins in which multiple protein components and a single RNA species are required for activity in vitro as well as in vivo. It is not known, however, which subunits participate directly in phosphodiester-bond hydrolysis. The RNA subunit of nuclear RNase P is evolutionarily related to its catalytically active bacterial counterpart, prompting speculation that in eukaryotes the RNA may be the catalytic component. In the bacterial RNase P reaction, Mg(II) is required to coordinate the nonbridging phosphodiester oxygen(s) of the scissile bond. As a consequence, bacterial RNase P cannot cleave pre-tRNA in which the pro-Rp nonbridging oxygen of the scissile bond is replaced by sulfur. In contrast, the RNase P reaction in plant chloroplasts is catalyzed by a protein enzyme whose mechanism does not involve Mg(II) coordinated by the pro-Rp oxygen. To determine whether the mechanism of nuclear RNase P resembles more closely an RNA- or a protein-catalyzed reaction, we analyzed the ability of Saccharomyces cerevisiae nuclear RNase P to cleave pre-tRNA containing a sulfur substitution of the pro-Rp oxygen at the cleavage site. Sulfur substitution at this position prohibits correct cleavage of pre-tRNA. Cleavage by eukaryotic RNase P thus depends on the presence of a thio-sensitive ligand to the pro-Rp oxygen of the scissile bond, and is consistent with a common, RNA-based mechanism for the bacterial and eukaryal enzymes.

Temporal and spatial distribution of interleukin-1 beta in balloon injured porcine coronary arteries

OBJECTIVE

Interleukin-1 beta (IL-1 beta) is a proinflammatory cytokine with a wide range of biological activities. We determined the distribution of IL-1 beta following percutaneous transluminal coronary angioplasty (PTCA) of porcine arteries, and the presence of caspase-1 (required for the activation of IL-1 beta).

METHODS

Oversized balloon angioplasty was performed in Yorkshire White pigs and the vessels excised at selected intervals (1, 6, 18 h, 3, 7, and 14 days) post-PTCA. IL-1 beta and caspase-1 were then identified using reverse transcription polymerase chain reaction (RT-PCR), in situ RT-PCR, and immunohistochemistry.

RESULTS

IL-1 beta protein was detected in the inflammatory infiltrate up to 3 days after PTCA. Luminal endothelial cells contained IL-1 beta at 1 h, with peak expression at 3-7 days. Adventitial capillaries were IL-1 beta-positive at all timepoints. IL-1 beta was detected in adventitial cells at 3 days, with reduced levels at 7 and 14 days. At 7 days, neointimal cells were also IL-1 beta positive. No IL-1 beta was detected in non-PTCA control arteries. RT-PCR demonstrated IL-1 beta mRNA expression to be induced at 1 h, and absent at 3 days. In situ RT-PCR revealed this expression to be distributed throughout the arterial layers at 6 h, but localized to the adventitia at 18 h, with a baseline expression in the adventitial layer of non-PTCA controls. Caspase-1 was detected in luminal endothelial cells from 6 h, in adventitial cells from 3 days, and in neointimal cells from 7 days post-PTCA. This expression colocalized with IL-1 beta, indicating the potential for the IL-1 beta present to become activated.

CONCLUSIONS

We conclude that IL-1 beta is synthesised, in conjunction with caspase-1, by endothelial, inflammatory, and adventitial cells early (within 3 days) after PTCA, with decreased levels at later timepoints, suggesting that it has a key role to play in the early stages of healing following PTCA.