A TRIM21-based bioPROTAC highlights the therapeutic benefit of HuR degradation

Human antigen R (HuR) is a ubiquitously expressed RNA-binding protein, which functions as an RNA regulator. Overexpression of HuR correlates with high grade tumours and poor patient prognosis, implicating it as an attractive therapeutic target. However, an effective small molecule antagonist to HuR for clinical use remains elusive. Here, a single domain antibody (VHH) that binds HuR with low nanomolar affinity was identified and shown to inhibit HuR binding to RNA. This VHH was used to engineer a TRIM21-based biological PROTAC (bioPROTAC) that could degrade endogenous HuR. Significantly, HuR degradation reverses the tumour-promoting properties of cancer cells in vivo by altering the HuR-regulated proteome, highlighting the benefit of HuR degradation and paving the way for the development of HuR-degrading therapeutics. These observations have broader implications for degrading intractable therapeutic targets, with bioPROTACs presenting a unique opportunity to explore targeted-protein degradation through a modular approach.

Abstract 6302: Structure-based and property-based drug design of AZD9574, a CNS penetrant PARP1 selective inhibitor and trapper

PARP inhibitors exploit defects in DNA repair pathways to selectively target cancerous cells via PARP1 catalytic inhibition and PARP1 trapping onto the DNA. All known clinical PARP1 inhibitors bind at the same site at the catalytic center of the enzyme. However, despite this resemblance they show immensely different outcomes in terms of response rate in the clinic due to their varying degree of PARP trapping ability. Moreover, the first-generation PARP inhibitors were not optimized for selectivity across the PARP family potentially driving undesirable side effects, including intestinal toxicity from tankyrase inhibition or hematological toxicity from PARP2 inhibition. There has been strong rationale for the use of PARP inhibitors in neuro-oncology. However, the first-generation PARP inhibitors have limited CNS distribution as these drugs were not designed for brain penetration. Recently AstraZeneca has reported the discovery of AZD5305, a next generation PARP1 selective inhibitor and PARP1-DNA trapper which was not designed with a CNS penetrant profile. Given the unmet need of a brain penetrant PARP1 inhibitor, we set out to identify a highly potent and selective PARP1 inhibitor and trapper with CNS profile. In our next generation PARP1 inhibitor, we sought to retain the profile of AZD5305 and lower the efflux for CNS penetration. Despite the challenge of narrow SAR, we successfully used the structure- and property-based design approach to identify a brain penetrant PARP1 inhibitor and PARP1-DNA trapper. We used multiple medicinal chemistry maneuvers such as masking the hydrogen bond donors and core modifications to lower the efflux in order to achieve brain penetration. Further optimization of the nicotinamide mimetic core for potency and metabolic stability led us to the discovery of AZD9574.AZD9574 shows improved selectivity for PARP1 over PARP2 vs AZD5305 and retains its excellent selectivity over other PARP family members. It has low efflux in Caco2, MDCK-MDR1, and MDCK-MDR1-BCRP permeability assays and it also showed CNS penetration in rat and cynomolgus monkey. AZD9574 has excellent secondary pharmacology and acceptable physicochemical properties and good PK in preclinical species.In vitro, AZD9574 selectively inhibits the growth of BRCAm cell lines. Importantly, AZD9574 showed efficacy in an intracranial BRCA1m MDA-MB-436 xenograft model at doses of 3, 10 and 30 mg/kg QD, significantly extending the survival of tumor-bearing mice compared to vehicle control arm.In summary, AZD9574 is a next generation selective PARP1 inhibitor and trapper with CNS penetration. This profile makes it an ideal candidate for treating CNS malignancies or brain metastases that have a dependence on PARP inhibition either as single agent or in combination with other therapies.

Citation Format: Avipsa Ghosh, Sudhir M. Hande, Amber Balazs, Derek Barratt, Sabina Cosulich, Barry Davies, Sébastien Degorce, Kevin Embrey, Sonja Gill, Anders Gunnarsson, Giuditta Illuzzi, Peter Johnström, Jordan Lane, Carrie Larner, Rachel Lawrence, Elisabetta Leo, Andrew Madin, Elizabeth Martin, Lisa McWilliams, Lenka O’Connor, Mark O’Connor, Jonathan Orme, Fiona Pachl, Martin Packer, Andy Pike, Philip Rawlins, Marianne Schimpl, Magnus Schou, Anna Staniszewska, Wenzhan Yang, James Yates, Andrew Zhang, XiaoLa Zheng, Stephen Fawell, Petra Hamerlik, Jeffrey Johannes. Structure-based and property-based drug design of AZD9574, a CNS penetrant PARP1 selective inhibitor and trapper [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6302.

Abstract 296: Structure-based and property-based drug design of AZD5305, a highly selective PARP1 inhibitor and trapper

Since the approval of olaparib in 2014 for BRCA mutated (BRCAm) ovarian cancer, many PARP inhibitors have been developed and have seen widespread success. However, as a class, these drugs are not without adverse events which have limited their ability to be combined with chemotherapy. Most first generation PARP inhibitors were developed and optimized before the concept of PARP1-DNA trapping was discovered as the mechanism by which PARP inhibitors exert their synthetic lethal effects on BRCAm cells. Moreover, the first generation PARP inhibitors were not optimized for selectivity across the PARP family potentially driving undesirable side effects, including intestinal toxicity from tankyrase inhibition or hematological toxicity from PARP2 inhibition. With this in mind, we set out to discover a best-in-class, second generation PARP inhibitor that was highly selective for PARP1 over the other 16 members of the PARP family, as well as a highly potent PARP1-DNA trapper.

PARP1 and PARP2 have a highly similar amino acid sequence, and most of the residues around the nicotinamide binding site are identical. However, there are some key residue differences in the helical domain which serves a regulator of the nicotinamide binding pocket. The publication of NMS-P118 in 2015 by Nerviano Medical Sciences showed that a highly selective PARP1 inhibitor could be found. This work inspired us to screen an extensive list of previously reported PARP inhibitors for selectivity against PARP2 and we found that FR257516 met the selectivity criteria as previously reported, but lacked the ability to trap PARP1 to DNA and hence lacked any activity in a cell colony formation assay in DLD-1 BRCA2-/- cells. Using parallel chemistry to generate diverse analogs, X-ray crystallography to enable structure-based design, and exploration of multiple nicotinamide mimetic cores, we were able to generate lead compound AZ4554, which was a PARP1 selective PARP1-DNA trapper with potent activity in BRCAm cells. Using concepts of property-based drug design, we were able to optimize lead compound AZ4554 into candidate drug AZD5305, making key improvements in secondary pharmacology, including reducing hERG activity, and intrinsic clearance in human microsomes through the introduction of polar atoms to lower logD without compromising permeability or oral bioavailability.

AZD5305 is a highly selective binder of PARP1 over PARP2 and other PARP enzymes by fluorescence polarization, surface plasmon resonance, and single molecule spectroscopy. It is highly potent against DLD-1 BRCA2-/- cells, while sparing isogenic BRCA WT cells. The secondary pharmacology of AZD5305 is remarkably clean, with hERG activity >40 µM. AZD5305 has a very favorable pre-clinical PK profile, low predicted human dose, and has shown efficacy in an MDA-MB-436 mouse xenograft model.

Citation Format: Sudhir Hande, Amber Balazs, Sébastien L. Degorce, Kevin Embrey, Avipsa Ghosh, Sonja J. Gill, Anders Gunnarsson, Giuditta Illuzzi, Jordan Lane, Carrie Larner, Elisabetta Leo, Andrew Madin, Lisa McWilliams, Mark J. O'Connor, Jonathan Orme, Fiona Pachl, Martin Packer, Andy Pike, Philip Rawlins, Marianne Schimpl, Anna D. Staniszewska, Andrew Zhang, Xiaolan Zheng, Jeffrey W. Johannes. Structure-based and property-based drug design of AZD5305, a highly selective PARP1 inhibitor and trapper [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 296.

Abstract LB-A09: EED targeted PROTACs degrade EED, EZH2, and SUZ12 in the PRC2 complex

Deregulation of the PRC2 components EZH2, SUZ12, and EED plays critical roles in driving aberrant hypermethylation of H3K27 and tumorigenicity of many solid and hematological malignancies. Although SAM competitive small molecule inhibitors of EZH2 show promising clinical activity in PRC2-dependent cancers, preclinical data suggests that resistance can be acquired through secondary mutations in EZH2 that abrogate drug target engagement. To address these limitations, we have designed several hetero-bifunctional PROTACs (Proteolysis Targeting Chimera) to efficiently target EED for elimination. Our EED-targeting PROTACs bind to EED (pKD= 9.02-9.27) and promote stable ternary complex formation with the E3 ubiquitin ligase. The PROTACs potently inhibit PRC2 enzyme activity (pIC50= 8.11-8.17) that results in a decrease in H3K27me3 levels in cells. Interestingly, EED-targeting PROTACs induce rapid degradation of EED, as well as its associated proteins, including EZH2 and SUZ12 in the PRC2 complex. Inhibition of the ubiquitin proteasome pathway abrogates PROTAC-mediated degradation of EED and its associated proteins. Furthermore, the EED targeting PROTACs selectively inhibit proliferation and survival of PRC2-dependent cancer cells (GI50= 49-58 nM). In summary, our data demonstrate a novel therapeutic modality in treating PRC2 dependent cancer through PROTAC mediated platform.

Citation Format: Jessie Hao-Ru Hsu, Timothy Rasmusson, James Robinson, Fiona Pachl, Jon Read, Sameer Kawatkar, Daniel H O'Donovan, Sharan Bagal, Erin Code, Philip Rawlins, Argyrides Argyrou, Ronald Tomlinson, Ning Gao, Xiahui Zhu, Elisabetta Chiarparin, Kelly Jacques, Minhui Shen, Haley Woods, Emma Bednarski, David M. Wilson, Lisa Drew, M. Paola Castaldi, Stephen Fawell, Andrew Bloecher. EED targeted PROTACs degrade EED, EZH2, and SUZ12 in the PRC2 complex [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr LB-A09. doi:10.1158/1535-7163.TARG-19-LB-A09

Abstract 1647: Discovery of AZD0364, a potent and selective oral inhibitor of ERK1/2 that is efficacious in both monotherapy and combination therapy in models of NSCLC

The RAS/MAPK pathway is a major driver in oncogenesis and is dysregulated in approximately 30% of human cancers, primarily by mutations in BRAF or RAS genes. The extracellular-signal-regulated kinases (ERK1 and ERK2) serve as key central nodes within this pathway. The feasibility of targeting the RAS/MAPK pathway has been demonstrated by the initial clinical responses observed to BRAF and MEK inhibitors in BRAF V600E/K metastatic melanoma, however resistance frequently develops by reactivation of the pathway. Direct targeting of ERK1/2, may provide another therapeutic option in tumours with mutations in BRAF or RAS genes. Importantly, ERK1/2 inhibition may have clinical utility in overcoming acquired resistance to RAF and MEK inhibitors where RAS/MAPK pathway reactivation has occurred, such as relapsed BRAF V600E/K melanoma. Starting from our published work,1 we will describe for the first time, a scaffold hopping approach leading to the identification of AZD0364, a pre-clinical ERK1/2 inhibitor candidate drug. Driven by conformational modelling and structure-based design, and by utilising novel sulfamidate ring opening chemistry, a high lipophilicity efficiency core was identified. Structure based, multi-parameter based optimisation of this improved core ultimately led to AZD0364. AZD0364 exhibits high cellular potency against a direct downstream substrate on the MAPK pathway (e.g. inhibition of phospho-p90RSK1 in BRAFV600E mutant A375 cells, IC50 = 6 nM). The molecule is a highly selective kinase inhibitor (10/329 kinases tested are inhibited at >50% at a 1 µM) and has long residence time on the protein (as determined by SPR on human unphosphorylated-ERK2: pKd = 10; t1/2 = 277 mins). The good in vitro potency and selectivity is complemented by excellent physico-chemical properties (maximum absorbable dose estimated to be >4 g) and good oral pharmacokinetics across species, leading to a low predicted dose to man. In xenograft models, AZD0364 inhibits phospho-p90RSK1 in tumors in a dose-dependent manner. AZD0364 induces regressions in the KRAS mutant NSCLC Calu 6 xenograft model. AZD0364 can also be combined safely and effectively with the MEK1/2 inhibitor selumetinib in KRAS mutant NSCLC xenograft models. 1Richard A. Ward et. al. Structure-Guided Discovery of Potent and Selective Inhibitors of ERK1/2 from a Modestly Active and Promiscuous Chemical Start Point, J. Med. Chem. 2017, 60, 3438−3450.

Citation Format: Iain Simpson, Mark J. Anderton, David M. Andrews, Jason Breed, Emma Davies, Judit E. Debreczeni, Vikki Flemington, Francis D. Gibbons, Mark A. Graham, Philip Hopcroft, Tina Howard, Julian Hudson, Clifford D. Jones, Christopher Jones, Nicola Lindsay, J Elizabeth Pease, Philip Rawlins, Karen Roberts, Steve Swallow, Steve St-Gallay, Michael E. Tonge, Richard A. Ward. Discovery of AZD0364, a potent and selective oral inhibitor of ERK1/2 that is efficacious in both monotherapy and combination therapy in models of NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1647.

Can residence time offer a useful strategy to target agonist drugs for sustained GPCR responses?

Residence time describes the how long a ligand is bound to its target, and is attracting interest in drug discovery as a potential means of improving clinical efficacy by increasing target coverage. This concept, as originally applied to antagonists, is more complicated for G-protein-coupled receptor (GPCR) agonists because of the transiency of receptor responses (via desensitization and internalization). However, in some cases sustained GPCR agonist responses have been observed, with evidence consistent with a role for slow binding kinetics. We propose a model to explain our understanding of how residence time and rebinding might influence sustained signaling by internalized receptors. We also highlight the anticipated benefit for drug discovery of fully understanding and exploiting these phenomena to target desirable receptor response profiles selectively.

Sustained wash-resistant receptor activation responses of GPR119 agonists

G protein-coupled receptor 119 (GPR119) is involved in regulating metabolic homoeostasis, with GPR119 agonists targeted for the treatment of type-2 diabetes and obesity. Using the endogenous agonist oleoylethanolamide and a number of small molecule synthetic agonists we have investigated the temporal dynamics of receptor signalling. Using both a dynamic luminescence biosensor-based assay and an endpoint cAMP accumulation assay we show that agonist-driven desensitization is not a major regulatory mechanism for GPR119 despite robust activation responses, regardless of the agonist used. Temporal analysis of the cAMP responses demonstrated sustained signalling resistant to washout for some, but not all of the agonists tested. Further analysis indicated that the sustained effects of one synthetic agonist AR-231,453 were consistent with a role for slow dissociation kinetics. In contrast, the sustained responses to MBX-2982 and AZ1 appeared to involve membrane deposition. We also detect wash-resistant responses to AR-231,453 at the level of physiologically relevant responses in an endogenous expression system (GLP-1 secretion in GLUTag cells). In conclusion, our findings indicate that in a recombinant expression system GPR119 activation is sustained, with little evidence of pronounced receptor desensitization, and for some ligands persistent agonist responses continue despite removal of excess agonist. This provides novel understanding of the temporal responses profiles of potential drug candidates targetting GPR119, and highlights the importance of carefully examining the the mechanisms through which GPCRs generate sustained responses.

Hippocampal scrapie infection impairs operant DRL performance in mice

In differential reinforcement of low rates of responding (DRL) tasks, animals are trained to respond for rewards that become available only after some set time has elapsed since the animal's previous response. DRL performance is impaired by hippocampal lesions regardless of their precise location, and can be measured using automated operant equipment, whereas spatial tasks are selectively impaired by dorsal, but not ventral hippocampal lesions, and are typically conducted by hand. Earlier studies of prion infection following dorsal hippocampal micro-injections of scrapie have shown clear impairments of spatial alternation, but these occurred significantly later than dysfunction in hippocampus-dependent 'domestic' tasks such as nesting or burrowing. In the present experiment, mice were trained to respond on an automated DRL schedule prior to dorsal hippocampal ME7 scrapie injection. Post-operative DRL performance was monitored, along with performance on 'domestic' and other tests, which provided additional measures of disease progression. Animals with scrapie developed a clear DRL deficit at approximately the same time as their deficits on the other tests became apparent, and long before clinical signs were detectable. DRL deficits thus appeared earlier in the sequence of disease progression than previously reported for spatial alternation, suggesting that early signs of scrapie infection are caused in part by neuronal dysfunction extending beyond the dorsal hippocampal region of initial infection.

Measurement of von Willebrand factor activity: relative effects of ABO blood type and race

Tests based on three different principles are reported to measure the activity of von Willebrand factor (VWF): ristocetin cofactor (VWF:RCo), collagen binding (VWF:CB), and the so-called "activity ELISA" (VWF:MoAb). We measured these and other diagnostic parameters in a population of 123 randomly selected female study controls, age 18-45 years. Type O subjects had significantly lower levels than non-O subjects in each test. Race differences were seen in all tests except VWF:RCo, with Caucasians having significantly lower levels than African-Americans. ABO differences accounted for 19% of the total variance in VWF:Ag (P < 0.0001) and race for 7% (P < 0.0001), for a total of 26%. Both effects were mediated through VWF:Ag and were independent. VWF:Ag level was the primary determinant of VWF function, accounting for approximately 60% of the variance in VWF:RCo and VWF:CB and 54% of the variance in factor VIII. The ratio VWF:RCo/VWF:Ag differed significantly by race within blood group. The median ratios were 0.97 for type O Caucasians vs. 0.79 for type O African-Americans and 0.94 for non-O Caucasians vs. 0.76 for non-O African-Americans. The ratio VWF:CB/VWF:Ag did not vary. This suggests racial differences in the interaction of VWF with GP1b but not with subendothelium. Alternatively, VWF:RCo may be regulated to maintain a relatively constant plasma level in the presence of excessive VWF:Ag. This heterogeneity within the normal population is partially responsible for the difficulty in defining diagnostic limits for von Willebrand disease.

Novel reduced benzo[j]fluranthen-3-ones from Cladosporium cf. cladosporioides with cytokine production and tyrosine kinase inhibitory properties

A series of reduced benzo[j]fluoranthen-3-ones (1-4) was isolated from fermentations of a fungal strain CBUK20700 (CBS 100220), classified as Cladosporium cf. cladosporioides, during a microbial extract screening programme to identify inhibitors of anti-CD28-induced interleukin-2 (IL-2) production by Jurkat E6-1 cells as potential immunosuppressive agents. These compounds were also found to be tyrosine kinase inhibitors. The structures of compounds 1-4 were elucidated by spectroscopic methods including the HMQC, HMBC and NOESY NMR experiments. The most potent compound in the series, (6bS,7R,8S)-7-methoxy-4,8,9-trihydroxy-1,6b,7,8-tetrahydro-2H-benzo[j]fluoranthen-3-one (1) inhibited anti-CD28-induced IL-2 production and Abl tyrosine kinase with IC50 values of 400 and 60 nM respectively. The 6b-stereoisomeric 2 was a moderate inhibitor of both IL-2 production and Abl tyrosine kinase while the 8-oxo derivative 3 was inactive in both assays. The 8-O-methyl ether 4 was a moderate inhibitor of IL-2 production but exhibited potent inhibition of Abl tyrosine kinase with an IC50 of 45 nM.

Differential regulation of CD3- and CD28-induced IL-2 and IFN-γ production by a novel tyrosine kinase inhibitor XR774 from Cladosporium cf. cladosporioides

Inhibition of CD28 signalling after an immune response impedes T cell activation and can lead to immunosuppression. To identify inhibitors of anti-CD28 induced IL-2 production, a library of fungal metabolites was screened in a cell-based, high throughput assay. A reduced novel benzofluoranthene, tentatively named as (6bS, 7R, 8S)-7-methoxy-4, 8, 9-trihydroxy-1, 6b, 7, 8-tetrahydro-2H-benzo[j] fluoranthen-3-one (XR774), from Cladosporium cf. cladosporioides, was isolated. XR774 inhibited IL-2 mRNA and protein expression induced by anti-CD28 and anti-CD3 but had no effect on IL-2 induction by PMA and ionomycin. Moreover, XR774 inhibited the activity of the tyrosine kinases, Fyn, Lck, Abl and epidermal growth factor receptor (EGFR) with nanomolar activity, whereas micromolar concentrations of XR774 were ineffective on the serine-threonine kinase, PKA. Kinetic analysis of Fyn kinase inhibition was consistent with XR774 as a competitive inhibitor with respect to ATP. In peripheral blood, mononuclear cells (PBMC), XR774 inhibited anti-CD3 and anti-CD28 induced IL-2 and IL-2R alpha chain (CD25) expression but was consistently less active for inhibition of IFN-gamma production. On stimulation with PMA and anti-CD28, XR774 inhibited IL-2 production but had no effect on CD25 expression and enhanced IFN-gamma production. In contrast, the ansamycin, geldanamycin, inhibited both IL-2 and IFN-gamma production induced by anti-CD3 and anti-CD28 or PMA and anti-CD28. No significant associated cytotoxicity or inhibition of protein synthesis was observed at concentrations up to 14 microM. Thus, XR774 represents a novel class of pharmacological agent with selective biological activities that distinguish it from other natural product inhibitors, such as the ansamycins.

Venous thrombosis in relation to fibrinogen and factor VII genes among African-Americans

We evaluated the relation between venous thrombosis and plasma fibrinogen levels, the HaeIII and BcI polymorphisms of the beta fibrinogen gene, and the MspI polymorphisms of the factor VII gene in a case-control study of African-Americans. The study included 91 venous thrombosis cases and 185 control subjects obtained from a hospital in Atlanta, Georgia. High plasma fibrinogen was associated with increased risk of venous thrombosis, but the finding was not statistically significant. There was little association between the HaeIII polymorphisms and the BclI polymorphisms and the risk of venous thrombosis. The prevalence of the M2/M2 genotype of the factor VII gene was higher among cases than controls, but the difference was not statistically significant. The prevalence of the HaeIII H2 allele and the BclI B2 allele of the beta fibrinogen gene, both of which have been associated with slightly higher levels of plasma fibrinogen in most studies, is considerably lower among African-Americans in this study than it is among Whites in the United States and among Northern Europeans. The study is limited by its small size. However, despite this limitation, it supports the belief that increased plasma fibrinogen levels are associated with increased venous thrombosis risk. The study also indicated that the HaeIII and the BclI polymorphisms of the beta fibrinogen gene and the MspI polymorphisms of the factor VII gene are not strong determinants of venous thrombosis.

The role of the t-PA I/D and PAI-1 4G/5G polymorphisms in African-American adults with a diagnosis of myocardial infarction or venous thromboembolism

To determine whether or not the PAI-1 4G/5G and t-PA I/D polymorphisms in African-Americans were linked to cardiovascular disease, the association of these polymorphisms to disease expression was analyzed in a recently completed case-control study of myocardial infarction or venous thromboembolism among African-Americans. All African-Americans patients with a history of venous thromboembolism attending an anticoagulant clinic, and patients with a history of a MI attending a cardiology clinic at a large local urban public hospital were eligible for inclusion as cases in the study. In this study it was observed that there was a statistically significant association between the D allele of the t-PA I/D polymorphism and venous thromboembolism and a nonsignificant association between the D allele and myocardial infarction among African-Americans. t-PA antigen levels were statistically significantly higher among both myocardial infarction and venous thromboembolism cases compared with control subjects. The genotypes were unrelated to t-PA plasma levels. There was no association between either myocardial infarction or venous thromboembolism and the 4G/5G PAI-1 genotype. It was also found that genotype frequencies for both PAI-1 4G/5G and t-PA I/D polymorphisms in African-American adults were different from those reported for both U.S. Causcians and Europeans.

Inhibition of endotoxin-induced TNF-alpha production in macrophages by 5Z-7-oxo-zeaenol and other fungal resorcylic acid lactones

Resorcylic acid lactones are fungal metabolites that exhibit a wide range of biological properties which includes oestrogenic, antifungal, phytotoxic and anti-inflammatory activity. The capacity of 5Z-7-oxo-zeaenol, a resorcylic lactone of fungal origin and six naturally occurring analogues to inhibit lipopolysaccharide (LPS)-induced cytokine production in phorbol 12-myristate-13-acetate (PMA)-treated cultured myelomonocytic cells (U937) was compared. The activity of the natural analogues in the U937 assay varied over 10(4)-fold, with 5Z-7-oxo-zeaenol the most potent of those tested inhibiting tumour necrosis factor-alpha (TNF alpha) production in these cells with IC50 of 6 nM. The isomeric 7-oxo-zeaenol and structurally more distant monorden (radicicol) were the next most active compounds with IC50 approximately 500 nM, and zearalenone, the least active with IC50 > 400 microM. 5Z-7-oxo-zeaenol retained activity in LPS-stimulated peripheral blood mononuclear cells with an IC50 of 10-25 nM. This compound also inhibited LPS-induced TNF alpha production in whole blood experiments (IC50 100-1000 nM) and lowered serum levels of TNF alpha in mice when administered prior to LPS. 5Z-7-oxo-zeaenol was shown to inhibit the phosphorylation and activation of mitogen-activated protein kinase (MAPK) induced by LPS. These data are consistent with a mechanism of action at or upstream of MAPK with resultant downstream effects. This series of naturally occurring analogues represents an interesting group of compounds with diverse biological properties. Of this series, 5Z-7-oxo-zeanenol has exceptionally potent anti-inflammatory properties exhibited by its strong inhibition of cytokine production.

The relationship between polymorphisms in the endothelial cell nitric oxide synthase gene and the platelet GPIIIa gene with myocardial infarction and venous thromboembolism in African Americans

STUDY OBJECTIVES

To determine whether the polymorphic dinucleotide repeats found in intron 4 of the endothelial cell nitric oxide synthase (ecNOS) gene and the platelet GPIIIa PLA(1)/A(2) polymorphism are associated with myocardial infarction (MI) and venous thromboembolism (VTE) in African Americans. Because these two genes may interact physiologically, the third objective was to determine if there was a relationship between the polymorphisms with respect to MI and VTE.

DESIGN

A hospital-based case-control study. After informed consent was obtained, blood used for DNA extraction was drawn from the subjects.

SETTING

The study was conducted in the Anticoagulant Clinic and the Cardiology Clinic at Grady Memorial Hospital in Atlanta Georgia.

PATIENTS

Subjects were recruited from African-American patients with a reported history of MI (n = 110) or VTE (n = 91). Control subjects (n = 185) without a history of cardiovascular or venous disease were recruited from an outpatient clinic.

MEASUREMENTS AND RESULTS

The 393 ecNOS allele was more common among MI cases (36%; p = 0.01) and VTE cases (35%; p = 0.04) than among control subjects (26%). There was no association between the GPIIIa genotypes and either MI or VTE. However, among the MI subjects, there was a strong association between the ecNOS 393/393 genotype and the Pl(A2) allele. It was also found that the frequency of the 393 allele was higher in African-American persons (0.26) compared with what has been reported for Australian Caucasians (0. 14) and Japanese (0.10).

CONCLUSIONS

The 393 allele but not the Pl(A2) allele was significantly associated with both MI and VTE in African Americans. Homozygosity for the 393 allele was significantly associated to the diagnosis of MI prior to the age of 45. The combination of the 393 allele and a Pl(A2) allele was also highly associated with MI. The frequency of the 393 allele was significantly higher in African Americans than what has been reported for other populations. This study furthers not only extends the association of the 393 allele to VTE but has demonstrated an interaction with the Pl(A2) allele with respect to MI.

The effects of hippocampal and fimbria-fornix lesions on prepulse inhibition

The present experiments tested the effects of conventional (dorsal aspiration and electrolytic) and excitotoxic (N-methyl-D-aspartate [NMDA]) hippocampal lesions and fimbria-fornix (FF) transection on prepulse inhibition (PPI) of startle response and on open-field activity. Activity was increased by FF transection and by conventional but not excitotoxic hippocampal lesions; complete NMDA lesion increased amphetamine-induced activity. Whereas dorsal hippocampal aspiration lesion disrupted PPI, the phenomenon was not affected by dorsal hippocampal electrolytic lesion, partial or complete excitotoxic (NMDA) hippocampal lesions, or complete FF transection, which interrupted the cholinergic input to the hippocampus as well as the hippocampal-subicular input to the nucleus accumbens. Systemic apomorphine disrupted PPI in both FF-transected rats and their controls. It is suggested that the hippocampus is essential for PPI disruption rather than for PPI expression.

Patient management of cerebral origin spasticity with intrathecal baclofen

Controlled, continuous intrathecal infusion of baclofen injection relieves severe spasticity for a wide range of patients. This therapy has become a standard treatment option in spasticity management programs. Multidisciplinary teams, coordinated by an experienced neuroscience practitioner, provide treatment in five phases. Experience from clinical trials and commercial use of this treatment provides a guide for others who are initiating this therapy at their facility. Further prospective research is needed to accurately determine best clinical practice guidelines for cost effective use of this therapy.

Relation of three genetic traits to venous thrombosis in an African-American population

A mutation in the Factor V gene (Factor V Leiden), a variant in the 5,10-methylenetetrahydrofolate reductase gene (MTHFR), and an insertion/deletion polymorphism of the angiotensin I-converting enzyme gene (ACE) may be related to abnormal blood clotting. The authors examined the associations between these genetic traits and venous thrombosis among African Americans. This study comprised 93 patients with venous thrombosis and 185 control subjects attending clinics at an urban, public hospital in Atlanta, Georgia, in 1995-1996. Subjects' DNA was extracted from blood and assayed for these genetic traits. Odds ratios were obtained from logistic regression and used as a measure of association between each genetic trait and venous thrombosis. Factor V Leiden was unrelated to venous thrombosis, but the mutation ws too rare among our African-American subjects to evaluate adequately its relation to venous thrombosis. The homozygous and heterozygous genotypes for the V allele of the MTHFR gene were unrelated to venous thrombosis (odds ratio = 0.9, 95% confidence interval 0.5-1.8). Subjects with the deletion/deletion ACE polymorphism experienced a moderate increase in venous thrombosis risk compared with persons with the other genotypes (odds ratio = 1.5, 95% confidence interval 0.9-2.6). However, women with this ACE genotype experienced no increased risk (odds ratio = 0.9, 95% confidence interval 0.5-1.9), whereas men with this genotype had nearly three times the risk (odds ratio = 2.8, 95% confidence interval 1.2-6.2; p value for interaction = 0.06). These data indicate that the prevalence of Factor V Leiden and the V allele of the MTHFR gene is low among African Americans. The D allele of the ACE gene is equally prevalent among African Americans and whites and may be related to venous thrombosis among African-American men.

Differential effects on TNF alpha production by pharmacological agents with varying molecular sites of action

This study describes the activation conditions for tumor necrosis factor-alpha (TNF alpha) production in myelomonocytic U937 cells and human primary peripheral blood monocytes in response to lipopolysaccharide (LPS) and/or phorbol 12-myristate 13-acetate (PMA). PMA itself induced only low levels of TNF alpha production with delayed kinetics (e.g. 0.758 +/- 0.128 ng/ml from U937 cells after 48 h) while LPS induced greater levels of TNF alpha production in less time (e.g. 2.083 +/- 0.96 ng/ml from monocytes in 24 h). Pharmacological agents with various molecular sites of action were used to validate the two systems, with the protein serine-threonine kinase inhibitors staurosporine and Ro-31-8220, the protein tyrosine kinase inhibitor herbimycin A (HBA) and dexamethasone exhibiting the greatest potency (IC50S 5-350 nM). In contrast to the effect on TNF alpha production, PMA induced strong phosphorylation/activation of p42/p44mapk in monocytes by 10 min determined in a mobility shift assay, while LPS was a weaker inducer. Additionally, staurosporine (to LPS and PMA) and HBA (to LPS only) inhibited the activation of these mitogen-activated protein kinase (MAPK) isoforms at doses 10-100 fold higher than those required to inhibit maximal TNF alpha production. These data indicate the involvement of the p42/p44mapk signalling pathway in LPS-induced pro-inflammatory cytokine production but suggest that other signalling pathways are also implicated in this phenomenon.

A racial difference in the prevalence of the Arg506-->Gln mutation

Several recent studies have reported that the factor V Arg506-->Gln mutation is present in 3-10% of adults of European descent. To determine if the prevalence is comparable among Blacks, we have initiated a case-control study in a large urban hospital in Atlanta which serves a substantial black population. We have evaluated 131 black subjects with confirmed venous or arterial thrombosis and 61 black subjects without a history of thrombosis. Only one case and one control were positive for the Arg506-->Gln mutation. We conclude that the mutation is more common among Whites than Blacks.

Intrathecal baclofen for spasticity of cerebral palsy: project coordination and nursing care

Spasticity caused by cerebral palsy is painful and disabling. Infusion of an intrathecal antispasmodic for relief is investigated in a multicenter, interdisciplinary clinical trial. Clinical nurse specialists coordinate local team endeavors. The nursing process serves as a functional framework for project development, protocol implementation and long-term patient follow-up.