OP0237 THROMBOEMBOLIC SAFETY PROFILE OF TOFACITINIB AND BARICITINIB: AN ANALYSIS OF WHO VIGIBASE

Background:

The Janus Kinase (JAK) inhibitors tofacitinib and baricitinib are new targeted treatments for rheumatoid arthritis. Recent concerns regarding the risk of thrombosis have led to warnings by the European Medicines Agency (EMA) and the Food and Drug Administration (FDA)1,2.

Objectives:

To examine the safety reporting of tofacitinib and baricitinib, with focus on thromboembolic events.

Methods:

Individual case safety reports (ICSRs) for tofacitinib and baricitinib were retrieved from the World Health Organization (WHO) global database (VigiBase) in April 2019. The primary outcomes were deep vein thrombosis (DVT) and pulmonary thrombosis (PT) or pulmonary embolism (PE). A disproportionality analysis was conducted by estimating the reporting odds ratio (ROR) and 95% confidence intervals (CIs) to compare the observed versus expected reporting ratio of DVT or PT|PE for tofacitinib or baricitinib. The ROR were calculated worldwide and stratifying by reporting from Europe or the US. In a secondary analysis, further thrombotic-related outcomes were investigated.

Results:

In both tofacitinib (n=40,017) and baricitinib (n=2,138) ICSRs, patients with reported DVT or PT|PE were older and had higher reporting of pro-thrombotic medications (e.g., contraceptives) or indicators of thromboembolic risk (i.e., antithrombotic treatment). The use of tofacitinib was associated with a significant increased reporting for DVT (ROR: 2.37 95% CI 1.23-4.56) and PT|PE (ROR 2.38 95% CI 1.45-3.89) in Europe. In the US, tofacitinib was only associated with an elevated reporting of PT (ROR: 2.05 % CI 1.45-2.90). Baricitinib was associated with a 3-fold increased risk of reporting for DVT (ROR: 3.47 95% CI 2.18-5.52) or PT|PE (ROR: 3.44 95% CI 2.43-4.88) in Europe, which accounted for 97% of all baricitinib ICSRs. Secondary thrombotic-related outcomes were poorly reported overall in VigiBase.

Conclusion:

This study supports the cautious use of JAK inhibitors in patients with rheumatoid arthritis who have a high thrombotic risk profile. Moreover, a potential class effect of JAK inhibitors cannot be ruled out.

References:

[1]FDA Drug Safety Communication. Safety trial finds risk of blood clots in the lungs and death with higher dose of tofacitinib (Xeljanz, Xeljanz XR) in rheumatoid arthritis patients; FDA to investigate. Food and Drug Administration (FDA)http://www.fda.gov/drugs/drug-safety-and-availability/safety-trial-finds-risk-blood-clots-lungs-and-death-higher-dose-tofacitinib-xeljanz-xeljanz-xr(2019).

[2]EMA confirms Xeljanz to be used with caution in patients at high risk of blood clots. EMA/608520/2019.https://www.ema.europa.eu/en/documents/referral/xeljanz-article-20-procedure-ema-confirms-xeljanz-be-used-caution-patients-high-risk-blood-clots_en.pdf(2019).

Acknowledgments:

We are thankful to every pharmacovigilance centre and contributor to the WHO Programme for International Drug Monitoring and VigiBase.

While the authors used data from the VigiBase, the WHO global database of ICSRs as a source of information, the conclusions do not represent the opinion of the Uppsala Monitoring Centre (UMC) or the WHO.

Disclosure of Interests:

Enriqueta Vallejo-Yagüe Employee of: Synovo GmbH 2012-2018 (not related to this abstract), Stefan Weiler Consultant of: Gedeon-Richter for drug safety 2017 (not related to this abstract), Andrea Michelle Burden: None declared

[YAP induces chromosomal instability in liver cancer patients]

BACKGROUND

The Hippo/YAP signaling pathway is a central regulator of organ growth and cell proliferation. Activation of the transcriptional co-activator and oncogene YAP (yes-associated protein) supports the development of liver cancer.

AIMS

The aim of this work was to analyze the molecular mechanisms which are responsible for YAP-induced hepatocarcinogenesis.

METHODS

YAP was silenced using siRNAs in liver cancer cell lines and effects on target gene expression were analyzed via real-time polymerase chain reaction (PCR) and western immunoblotting. Immunoprecipitation and chromatin immunoprecipitation was used to study interacting proteins and binding to target gene promoter regions, respectively. Transgenic mice with liver-specific and inducible YAP expression were used for in vivo analysis. Gene expression data from hepatocellular carcinoma (HCC) patients were used to analyze YAP-dependent gene signatures and to correlate with clinical data. HCC tissue microarrays were analyzed using immunohistochemistry.

RESULTS

Together with the transcription factors TEAD4 and FOXM1, YAP induces the expression of genes which are responsible for the development of chromosomal instability (CIN). The overexpression of these CIN genes characterizes liver cancer patients with a poor prognosis. Mechanistically, YAP/TEAD4 and FOXM1 bind to the promoter regions of the CIN genes to directly regulate their expression. The treatment of YAP-transgenic mice with a specific FOXM1 inhibitor reduces the YAP-dependent hepatomegaly, CIN gene expression and CIN. The analysis of human HCC tissue samples confirms the statistical correlation between YAP, FOXM1 and CIN.

DISCUSSION

These results reveal a new oncogenic mechanism of the Hippo/YAP signaling pathway and identify YAP and FOXM1 as potential targets for targeted therapies.

Snap-fits and upper limb functional limitations in German automotive workers

BACKGROUND

The use of snap-fit fasteners in automotive assembly has increased in the last 10 years. Their impact on musculoskeletal function of the upper limbs in assembly workers is not well described.

AIMS

To investigate the association between snap-fit assembly and upper limb functional limitations (ULFLs) in workers after a large-scale expansion of snap-fit assembly by a German automotive company.

METHODS

Cross-sectional data on blue-collar production workers' exposure to snap-fit assembly and ULFLs were collected from medical check-ups and company registers. The association between duration of snap-fit assembly and ULFLs, and the dose-response relationship between the two were analysed using logistic regression, adjusted for body mass index, gender and employment duration before snap-fit exposure.

RESULTS

The study group included 10722 workers. Within the company, 8.4, 6.9 and 10.3% were exposed to snap-fit 1-12, 13-24 and ≥25 months, respectively. After adjusting for confounders, snap-fit exposure for 1-12 months [odds ratio (OR) = 1.59, 95% confidence interval (CI) 0.88-2.88] and 13-24 months (OR = 1.48, 95% CI 0.76-2.88) was not statistically significantly associated with ULFLs compared with an unexposed group. However, exposure to ≥25 months of snap-fit assembly was statistically significant associated with ULFLs showing >2-fold risk (OR = 2.44, 95% CI 1.52-3.92). No clear dose-response relationship was found.

CONCLUSIONS

Our study suggests a negative long-term impact from snap-fit assembly on workers' upper limb function. Company physicians should be vigilant for signs of upper limb musculoskeletal disorders among workers exposed to snap-fit assembly.

Treatment of gout in a renal transplant patient leading to severe thrombocytopenia

WHAT IS KNOWN AND OBJECTIVE

Allopurinol (AP) inhibits the xanthine oxidase, which may indirectly lead to myelotoxicity when used in combination with azathioprine (AZA).

CASE SUMMARY

A 79-year-old female developed symptomatic thrombocytopenia after combination therapy with AZA (75 mg/day) and AP (100 mg/day) - after AP had been stopped. Concentrations of the myelotoxic 6-thioguanine-nucleotides metabolite of AZA were increased. Thrombocyte counts normalized within 8 days of discontinuation of AZA.

WHAT IS NEW AND CONCLUSION

The effect of a drug interaction in a patient with decreased elimination capacity may take several weeks to become apparent and may in fact do so even after the drug has been stopped. Concurrent AZA and AP therapy demands cautious use.

Mollow quintuplets from coherently excited quantum dots

Charge-neutral excitons in semiconductor quantum dots (QDs) have a small finite energy separation caused by the anisotropic exchange splitting. Coherent excitation of neutral excitons will generally excite both exciton components, unless the excitation is parallel to one of the dipole axes. We present a polaron master equation model to describe two-exciton pumping using a coherent continuous wave pump field in the presence of a realistic anisotropic exchange splitting. We predict a five-peak incoherent spectrum, namely a Mollow quintuplet under general excitation conditions. We experimentally confirm such spectral quintuplets for In(Ga)As QDs and obtain very good agreement with theory.

Teicoplanin pharmacokinetics in critically ill patients on continuous veno-venous hemofiltration

Pharmacokinetics of teicoplanin (TP) was assessed in critically ill patients on continuous veno-venous hemofiltration (CVVH), in eleven patients, after the first dose and in another four after repeated administration. The TP peak concentration amounted to 55.44 +/- 15.90 microg/ml and 81.28 +/- 28.55 microg/ml (mean +/- SD), the trough concentration 6.4 +/- 1.7 microg/ml and 21.3 +/- 5.0 microg/ml, the half-life 15.7 +/- 5.7 and 35.1 +/- 12.3 h, the apparent volume of distribution 0.84 +/- 0.22 and 0.48 +/- 0.09 l/kg and the TP clearance 39 +/- 12 and 11 +/- 4 ml/h/kg after the first dose and after repeated administration, respectively. The mean sieving coefficient of TP was 0.15. After a 1,200 mg loading dose, daily maintenance doses of 600 - 1,800 mg were required for achieving trough levels of 15 - 25 microg/ml. Therapeutic drug monitoring is indispensable during CVVH because of a considerable variability of TP pharmacokinetics.

Children's blood lead and standardized test performance response as indicators of neurotoxicity in metropolitan New Orleans elementary schools

This study analyzes pre-Katrina variation in aggregate student performance and children's blood lead (BPb) in 117 elementary school districts in metropolitan New Orleans. Fourth grade student achievement on Louisiana Educational Assessment Program (LEAP) tests were analyzed as a function of BPb for children 1-6 years old within school districts, controlling for student-teacher ratios, percent of students eligible for a free or discounted lunch, and school racial demography. Measures of performance across subject areas (English Language Arts, Science, Mathematics, and Social Studies) include school Achievement Test Scores (ATS) and indices of agreement and variation in student achievement. ATS are measured on a 5-point scale, corresponding to achievement categories of advanced=5 to unsatisfactory=1. Regression results show that median BPb (microg/dL) and percent of children with BPb > or =10 microg/dL are significantly associated with reductions in test scores across all subjects and depress variation in student performance across achievement categories. These data suggest that assisting children with improved school performance requires alleviation of pre-school Pb exposure and its associated neurotoxic damage. Cost-benefit calculations suggest that it is more cost effective to pay for onetime primary prevention instead of paying continuous expenses focused on reversing neurotoxic damage.

Backbone dynamics for the wild type and a double H52R/T56W mutant of the vnd/NK-2 homeodomain from Drosophila melanogaster

The (15)N relaxation behavior and heteronuclear Overhauser effect data for the wild type and an H52R/T56W double mutant protein that encompasses the vnd/NK-2 homeodomain from Drosophila melanogaster were used to characterize and describe the protein backbone dynamics. This investigation, which includes a description of a model structure for the H52R/T56W double mutant vnd/NK-2 homeodomain, was carried out for the two proteins in both the free and DNA-bound states. The double residue replacement at positions 52 and 56 within the DNA recognition helix of vnd/NK-2 has been shown to lead to a significant secondary structural modification resulting in an increase in the length of the recognition helix for the unbound protein. These structural changes are accompanied by corresponding changes in the T(1) and T(1)(rho) relaxation times as well as in the heteronuclear Overhauser effect (XNOE) values that show that the structural stability of the protein is enhanced by the two residue replacements. The values of the rotational anisotropy, D(parallel)/D(perpendicular), derived from analysis of the (15)N T(1) and T(1)(rho) relaxation values are small (1.189 for the unbound homeodomain and 1.110 for the bound homeodomain; both analyzed as prolate ellipsoids of revolution). A comparison of the T(2) values of the wild type and double mutant homeodomain reveals the presence of a low-frequency exchange contribution for the wild type analogue. These relaxation studies show that the motional behavior of the protein primarily reflects the tertiary structure and stability of the homeodomain backbone as well as the respective changes induced upon site-directed residue replacement or DNA binding.

BCL-2, BCL-X(L) sequester BH3 domain-only molecules preventing BAX- and BAK-mediated mitochondrial apoptosis

Critical issues in apoptosis include the importance of caspases versus organelle dysfunction, dominance of anti- versus proapoptotic BCL-2 members, and whether commitment occurs upstream or downstream of mitochondria. Here, we show cells deficient for the downstream effectors Apaf-1, Caspase-9, or Caspase-3 display only transient protection from "BH3 domain-only" molecules and die a caspase-independent death by mitochondrial dysfunction. Cells with an upstream defect, lacking "multidomain" BAX, BAK demonstrate long-term resistance to all BH3 domain-only members, including BAD, BIM, and NOXA. Comparison of wild-type versus mutant BCL-2, BCL-X(L) indicates these antiapoptotics sequester BH3 domain-only molecules in stable mitochondrial complexes, preventing the activation of BAX, BAK. Thus, in mammals, BH3 domain-only molecules activate multidomain proapoptotic members to trigger a mitochondrial pathway, which both releases cytochrome c to activate caspases and initiates caspase-independent mitochondrial dysfunction.

The vnd/NK-2 homeodomain: thermodynamics of reversible unfolding and DNA binding for wild-type and with residue replacements H52R and H52R/T56W in helix III

The conformational stabilities of the vnd (ventral nervous system defective)/NK-2 homeodomain [HD(wt); residues 1-80 that encompass the 60-residue homeodomain] and those harboring mutations in helix III of the DNA recognition site [HD(H52R) and HD(H52R/T56W)] have been investigated by differential scanning calorimetry (DSC) and ellipticity changes at 222 nm. Thermal unfolding reactions at pH 7.4 are reversible and repeatable in the presence of 50-500 mM NaCl with DeltaC(p) = 0.52 +/- 0.04 kcal K(-1) mol(-1). A substantial stabilization of HD(wt) is produced by 50 mM phosphate or by the addition of 100-500 mM NaCl to 50 mM Hepes, pH 7.4, buffer (from T(m) = 35.5 degrees C to T(m) 43-51 degrees C; DeltaH(vH) congruent with 47 +/- 5 kcal mol(-1)). The order of stability is HD(H52R/T56W) > HD(H52R) > HD(wt), irrespective of the anions present. Progress curves for ellipticity changes at 222 nm as a function of increasing temperature are fitted well by a two-state unfolding model, and the cooperativity of secondary structure changes is greater for mutant homeodomains than for HD(wt) and also is increased by adding 100 mM NaCl to Hepes buffer. A 33% quench of the intrinsic tryptophanyl residue fluorescence of HD(wt) by phosphate binding (K(D)' = 2.6 +/- 0.3 mM phosphate) is reversed approximately 60% by DNA binding. Thermodynamic parameters for vnd/NK-2 homeodomain proteins binding sequence-specific 18 bp DNA have been determined by isothermal titration calorimetry (10-30 degrees C). Values of DeltaC(p) are +0.25, -0.17, and -0.10 +/- 0.04 kcal K(-1) mol(-1) for HD(wt), HD(H52R), and HD(H52R/T56W) binding duplex DNA, respectively. Interactions of homeodomains with DNA are enthalpically controlled at 298 K and pH 7.4 with corresponding DeltaH values of -6.6 +/- 0.5, -10.8 +/- 0.1, and -9.0 +/- 0.6 kcal mol(-1) and DeltaG' values of -11.0 +/- 0.1, -11.0 +/- 0.1, and -11.3 +/- 0.3 kcal mol(-1) with a binding stoichiometry of 1.0 +/- 0.1. Thermodynamic parameters for DNA binding are not predicted from homeodomain structural changes that occur upon complexing to DNA and must reflect also solvent and possibly DNA rearrangements.

Expression studies and mutational analysis of the androgen regulated homeobox gene NKX3.1 in benign and malignant prostate epithelium

PURPOSE

The NKX-3.1gene is an androgen regulated prostate specific homeobox gene that is believed to have a vital role in normal prostate development. In mice the homologue NKx3.1 is exclusively expressed in prostate epithelium. In humans NKX3.1 expression is also restricted to the prostate but to our knowledge the cellular location has not been described. Furthermore, since NKX3.1 maps to chromosomal band 8p21, a region with high loss of heterozygosity in prostate cancer, the gene has been proposed to have tumor suppressor function. In this study we demonstrate that in human prostates NKX3.1 is expressed exclusively in secretory epithelial cells and the level of NKX3.1 expression remains invariant in normal tissue and in tissue showing various grades of prostate cancer. In the 19 cases examined the DNA sequences of the NKX3.1 gene were identical and no mutation was detected.

MATERIALS AND METHODS

Frozen tissue from patients who underwent radical prostatectomy was used for this study. For in situ hybridization experiments a 377 bp fragment corresponding to a portion of the 3' untranslated region of the NKX3.1 gene was amplified by polymerase chain reaction and cloned into the pCRII plasmid vector Invitrogen. Antisense or sense [33P] uridine triphosphate labeled RNA probes were generated with SP6 or T7 RNA polymerase and hybridized to the tissue sections. Slides were exposed to photographic emulsion and visualized on autoradiography. Laser capture microdissection was performed to procure pure populations of malignant epithelium. DNA was isolated by digesting samples in proteinase K buffer. Polymerase chain reaction and direct sequencing was performed using standard protocols.

RESULTS

In vitro hybridization showed that NKX3.1 expression was restricted to secretory epithelial cells within benign prostate glands. No expression was detected in stroma or infiltrating lymphocytes. NKX3.1 was expressed in all grades of malignant epithelium in all 25 cases examined. Direct sequencing of the coding region of NKX3.1 revealed the wild-type sequence in all 18 microdissected cancers analyzed.

CONCLUSIONS

Based on our studies we propose that NKX3.1 gene expression is restricted to benign and malignant secretory epithelium within the prostate but NKX3.1 does not appear to be a classic tumor suppressor gene responsible for prostate cancer initiation. These findings are consistent with the role of NKX3.1 in the development of normal prostate epithelium and maintenance of normal secretory function. Thus, NKX3.1 may represent a useful molecular marker for benign and malignant prostate epithelium.

Pro-apoptotic cascade activates BID, which oligomerizes BAK or BAX into pores that result in the release of cytochrome c

We review data supporting a model in which activated tBID results in an allosteric activation of BAK, inducing its intramembranous oligomerization into a proposed pore for cytochrome c efflux. The BH3 domain of tBID is not required for targeting but remains on the mitochondrial surface where it is required to trigger BAK to release cytochrome c. tBID functions not as a pore-forming protein but as a membrane targeted and concentrated death ligand. tBID induces oligomerization of BAK, and both Bid and Bak knockout mice indicate the importance of this event in the release of cytochrome c. In parallel, the full pro-apoptotic member BAX, which is highly homologous to BAK, rapidly forms pores in liposomes that release intravesicular FITC-cytochrome c approximately 20A. A definable pore progressed from approximately 11A consisting of two BAX molecules to a approximately 22A pore comprised of four BAX molecules, which transported cytochrome c. Thus, an activation cascade of pro-apoptotic proteins from BID to BAK or BAX integrates the pathway from surface death receptors to the irreversible efflux of cytochrome c. Cell Death and Differentiation (2000) 7, 1166 - 1173

Posttranslational N-myristoylation of BID as a molecular switch for targeting mitochondria and apoptosis

Many apoptotic molecules relocate subcellularly in cells undergoing apoptosis. The pro-apoptotic protein BID underwent posttranslational (rather than classic cotranslational) N-myristoylation when cleavage by caspase 8 caused exposure of a glycine residue. N-myristoylation enabled the targeting of a complex of p7 and myristoylated p15 fragments of BID to artificial membranes bearing the lipid composition of mitochondria, as well as to intact mitochondria. This post-proteolytic N-myristoylation serves as an activating switch, enhancing BID-induced release of cytochrome c and cell death.

tBID, a membrane-targeted death ligand, oligomerizes BAK to release cytochrome c

TNFR1/Fas engagement results in the cleavage of cytosolic BID to truncated tBID, which translocates to mitochondria. Immunodepletion and gene disruption indicate BID is required for cytochrome c release. Surprisingly, the three-dimensional structure of this BH3 domain-only molecule revealed two hydrophobic alpha-helices suggesting tBID itself might be a pore-forming protein. Instead, we demonstrate that tBID functions as a membrane-targeted death ligand in which an intact BH3 domain is required for cytochrome c release, but not for targeting. Bak-deficient mitochondria and blocking antibodies reveal tBID binds to its mitochondrial partner BAK to release cytochrome c, a process independent of permeability transition. Activated tBID results in an allosteric activation of BAK, inducing its intramembranous oligomerization into a proposed pore for cytochrome c efflux, integrating the pathway from death receptors to cell demise.

Phemx, a novel mouse gene expressed in hematopoietic cells maps to the imprinted cluster on distal chromosome 7

Phemx (Pan hematopoietic expression) is a novel murine gene expressed in developmentally regulated sites of hematopoiesis from early in embryogenesis through adulthood. Phemx is expressed in hematopoietic progenitors and mature cells of the three main hematopoietic lineages. Conceptual translation of the murine Phemx cDNA predicts a 25-kDa polypeptide with four hydrophobic regions and several potential phosphorylation sites, suggestive of a transmembrane protein involved in cell signaling. The PHEMX protein is structurally similar to tetraspanin CD81 (TAPA-1), a transmembrane protein involved in leukocyte activation, adhesion, and proliferation. Phemx maps to the distal region of chromosome 7, a segment of the mouse genome that contains a cluster of genes that exhibit genomic imprinting. However, imprinting analysis of Phemx at the whole organ level shows that it is biallelically expressed, suggesting that mechanisms leading to monoallelic expression are not imposed at this locus. The human PHEMX ortholog is specifically expressed in hematopoietic organs and tissues and, in contrast to murine Phemx, undergoes alternative splicing. The unique mode and range of Phemx expression suggest that it plays a role in hematopoietic cell function.

Recombinant green fluorescent protein-expressing human cytomegalovirus as a tool for screening antiviral agents

A recombinant human cytomegalovirus (AD169-GFP) expressing green fluorescent protein was generated by homologous recombination. Infection of human fibroblast cultures with AD169-GFP virus produced stable and readily detectable amounts of GFP signals which were quantitated by automated fluorometry. Hereby, high levels of sensitivity and reproducibility could be achieved, compared to those with the conventional plaque reduction assay. Antiviral activities were determined for four reference compounds as well as a set of putative novel cytomegalovirus inhibitors. The results obtained were exactly in line with the known characteristics of reference compounds and furthermore revealed distinct antiviral activities of novel in vitro inhibitors. The fluorometric data could be confirmed by GFP-based flow cytometry and fluorescence microscopy. In addition, laboratory virus variants derived from the recombinant AD169-GFP virus provided further possibilities for study of the characteristics of drug resistance. The GFP-based antiviral assay appeared to be very reliable for measuring virus-inhibitory effects in concentration- and time-dependent fashions and might also be adaptable for high-throughput screenings of cytomegalovirus-specific antiviral agents.

Postulated biogenesis of WS9885B and progress toward an enantioselective synthesis

[formula: see text] WS9885B promotes the assembly of microtubules in vitro and displays cytotoxicity as potent as paclitaxel against several cancer cell lines. In this Letter, we propose a biogenesis for this architecturally complex bacterial metabolite from a much simpler, polyunsaturated precursor. We also present significant progress toward a convergent, enantioselective synthesis of WS9885B. Our work features a chemoselective palladium-catalyzed cross-coupling of two advanced building blocks and an uncommon Claisen-like cyclization.

Relationship between Helicobacter pylori infection, histological gastritis, and functional dyspepsia

BACKGROUND/AIMS

It is still controversial as to whether or not Helicobacter pylori (H. pylori) infection, histological gastritis, and functional dyspepsia (FD) are intercorrelated. We prospectively evaluated patients with functional dyspepsia in an attempt to clarify this issue.

METHODOLOGY

Eighty-eight consecutive patients with functional dyspepsia (age range: 18-84 years) who did not show disease(s) other than gastritis were investigated. In a questionnaire they were asked to report the presence or absence of 8 upper gastrointestinal (GI) symptoms and to score them from 0 (absence) to 3 (severe), whereupon a sum score was calculated. Forty age-matched subjects with a sum score of <3 served as controls. Biopsy specimens for histology, bacterial culture, and rapid urease test were taken. A C13-urease breath test was also performed in 122 subjects.

RESULTS

H. pylori infection was present in 43% of patients with functional dyspepsia and 35% of control subjects (not significant (n.s.)). None of the symptoms were correlated with H. pylori infection. The median symptom sum score was 8.5 in H. pylori-positive and 9.5 in H. pylori-negative patients with functional dyspepsia (n.s.). Histological gastritis was strongly associated with H. pylori infection but was not correlated with any of the symptoms.

CONCLUSIONS

In a prospective population of patients with functional dyspepsia, H. pylori infection or gastritis are not associated with specific or severe symptoms. Our data imply that H. pylori gastritis is not an important condition in the pathogenesis of dyspeptic complaints.

Structural basis of an embryonically lethal single Ala --> Thr mutation in the vnd/NK-2 homeodomain

The structural and DNA binding behavior is described for an analog of the vnd/NK-2 homeodomain, which contains a single amino acid residue alanine to threonine replacement in position 35 of the homeodomain. Multidimensional nuclear magnetic resonance, circular dichroism, and electrophoretic gel retardation assays were carried out on recombinant 80-aa residue proteins that encompass the wild-type and mutant homeodomains. The mutant A35T vnd/NK-2 homeodomain is unable to adopt a folded conformation free in solution at temperatures down to -5 degreesC in contrast to the behavior of the corresponding wild-type vnd/NK-2 homeodomain, which is folded into a functional three-dimensional structure below 25 degreesC. The A35T vnd/NK-2 binds specifically to the vnd/NK-2 target DNA sequence, but with an affinity that is 50-fold lower than that of the wild-type homeodomain. Although the three-dimensional structure of the mutant A35T vnd/NK-2 in the DNA bound state shows characteristic helix-turn-helix behavior similar to that of the wild-type homeodomain, a notable structural deviation in the mutant A35T analog is observed for the amide proton of leucine-40. The wild-type homeodomain forms an unusual i,i-5 hydrogen bond with the backbone amide oxygen of residue 35. In the A35T mutant this amide proton resonance is shifted upfield by 1.27 ppm relative to the resonance frequency for the wild-type analog, thereby indicating a significant alteration of this i,i-5 hydrogen bond.

Site-directed mutations in the vnd/NK-2 homeodomain. Basis of variations in structure and sequence-specific DNA binding

Secondary structures, DNA binding properties, and thermal denaturation behavior of six site-directed mutant homeodomains encoded by the vnd/NK-2 gene from Drosophila melanogaster are described. Three single site H52R, Y54M, and T56W mutations, two double site H52R/T56W and Y54M/T56W mutations, and one triple site H52R/Y54M/T56W mutation were investigated. These positions were chosen based on their variability across homeodomains displaying differences in secondary structure and DNA binding specificity. Multidimensional NMR, electrophoretic mobility shift assays, and circular dichroism spectropolarimetry studies were carried out on recombinant 80-amino acid residue proteins containing the homeodomain. Position 56, but more importantly position 56 in combination with position 52, plays an important role in determining the length of the recognition helix. The H52R mutation alone does not affect the length of this helix but does increase the thermal stability. Introduction of site mutations at positions 52 and 56 in vnd/NK-2 does not modify their high affinity binding to the 18-base pair DNA fragment containing the vnd/NK-2 consensus binding sequence, CAAGTG. Site mutations involving position 54 (Y54M, Y54M/T56W, and H52R/Y54M/T56W) all show a decrease of 1 order of magnitude in their binding affinity. The roles in structure and sequence specificity of individual atom-atom interactions are described.

Qualitative and semi-quantitative value of a modified 13C-urea breath test for identification of Helicobacter pylori infection

OBJECTIVE

The 13C-urea breath test (13C-UBT) is the method of choice in evaluating the success of therapy for eradication of Helicobacter pylori infection. For reasons of cost efficiency and practicability, urea dose and measurement duration have been reduced and the DOB (delta over baseline) cutoff level with the highest predictive value determined. Further, the efficacy of the modified 13C-UBT as a semi-quantitative test method was evaluated by comparison with histologically determined bacterial infiltration.

METHODS

In a prospective study, a modified 13C-UBT with reduced urea dose (75 mg) and shortened measurement duration (30 min) was administered to 145 patients. The DOB cutoff with the highest predictive value was determined using relative operating characteristic analysis. Reference methods included histology, bacterial culture and the rapid urease test. The DOB value was compared with the histologically determined grade of bacterial infiltration and the correlation evaluated using the Spearman ranking method.

RESULTS

Reduction of the DOB cutoff level from 5.0 per thousand to 3.5 per thousand led to significant improvement in sensitivity (78.9% vs. 91.2%) and accuracy (88.6% vs. 90.2%) of the 13C-UBT. Only five of 57 infected patients were incorrectly reported as non-infected after modification of the DOB level. In two of three patients in whom histological findings were negative but the 13C-urease test positive, bacterial growth was observed at culture. The DOB level correlated significantly with histological grade of bacterial infection.

CONCLUSION

The modified 13C-UBT proved to be a sensitive, practicable and cost-effective method for detecting H. pylori infection and permits a semi-quantitative estimation of bacterial infiltration.

Molecular biology of glucocerebrosidase and the treatment of Gaucher disease

The inherited deficiency of glucocerebrosidase results in a group of sphingolipid storage disorders referred to collectively as Gaucher disease. Study of the biochemistry and cell biology of glucocerebrosidase has made possible an effective enzyme replacement therapy for the disease. Definition of the molecular genetics of glucocerebrosidase has improved diagnostic capabilities and presents the exciting possibility of a cure through gene therapy.

Identification of the neurotrophic factor sequence of prosaposin

Prosaposin, recently identified as a neurotrophic factor (1), is the precursor of saposins A, B, C, and D. The neurotrophic activity of prosaposin resides in the saposin C domain. We have pinpointed the active sequence to a linear 12-mer located in the NH2-terminal sequence of saposin C (LIDNNKTEKEIL). Nanomolar concentrations of a 22-mer peptide encompassing this region stimulated neurite outgrowth and choline acetyltransferase activity, and prevented cell death in neuroblastoma cells. In primary cerebellar granule cells, the 22-mer also stimulated neurite outgroth. Studies of the neuroblastoma line NS20Y using a radiolabeled 18-mer from the neurotrophic region identified a high-affinity (Kd = 70 pM) binding site indicative of receptor-ligand interaction. The 22-mer stimulated protein phosphorylation of several proteins, some of which were tyrosine-phosphorylated after brief exposure similar to saposin C. Circular dichroism studies demonstrated that the 22-mer was converted from a random to a helical structure by addition of ganglioside GM1. The results are consistent with receptor-ligand binding by the peptide initiating a signal transduction cascade and resulting in neuronal differentiation.

Identification of the binding and activating sites of the sphingolipid activator protein, saposin C, with glucocerebrosidase

Saposin C is a sphingolipid activator protein of 8.5 kDa that activates lysosomal glucocerebrosidase. Previously, we synthesized and characterized a synthetic full-length human saposin C protein that displays 85% of the activity of the native saposin C. In this study we use shorter synthetic peptides derived from the saposin C sequence to map binding and activation sites. By determining the activity and kinetic constant (Kact) values of these peptides, we have identified two functional domains, each comprising a binding site adjacent to or partially overlapping with an activation site. Domains 1 and 2 are located within amino acid positions 6-34 and 41-60, respectively. The activation sites span residues 27-34 and 41-49, whereas binding sites encompass residues 6-27 and 45-60. Peptides containing the sequences of either domain displayed 90% of the activity of the full-length synthetic saposin C. Domain 2, however, bound to glucocerebrosidase by at least an order of magnitude more strongly than domain 1. Binding sites within these domains contain sequences that are excellent candidates for forming amphipathic helical structures. Competition assays demonstrated that the binding of one domain to glucocerebrosidase prevents binding of the other domain, and that saposin A and saposin C bind to the same sites on glucocerebrosidase. A model predicting a saposin C:glucocerebrosidase complex with a stoichiometry of 4:2, respectively, is presented.

Position of the sulfhydryl group and the disulfide bonds of human glucocerebrosidase

Purified human glucocerebrosidase isolated from placenta was modified with [14C]-iodoacetic acid without reduction and digested with both protease-V8 at pH 4.0 followed by alpha-chymotrypsin at pH 7.5. The majority of radioactivity was found in a peptide that contained the [14C]-carboxymethylated-cysteine identified as CM-Cys18. Direct sequencing of the N-terminus of the intact labeled protein confirmed the modification of Cys18. For identification of disulfide bond-containing peptides, another portion of glucocerebrosidase was alkylated with nonlabeled iodoacetic acid and then digested with protease V8 and alpha-chymotrypsin as before. Twenty-eight HPLC fragments were collected. These purified peaks were then reduced with beta-mercaptoethanol followed by S-carboxymethylation with [14C]-iodoacetic acid. Three peptides among these 28 peptides generated two radioactive daughter peptides. These peptides were sequenced and the position of the radioactive CM-cysteines identified. The locations of these disulfides are Cys4-Cys16, Cys23-Cys342, and Cys126-Cys248. Attempts to reproduce the free sulfhydryl labeling experiments using the glucocerebrosidase isolated from Ceredase proved unsuccessful. No label was incorporated by this enzyme prior to reduction. This result suggests that the form of the protein used in the clinic differs from the native protein.

[The long-term functional results following velopharyngoplasty as a speech-improving measure]

Forty three out of 148 patients who had undergone velopharyngeal flap graft between 1980 and 1992 to treat velopharyngeal insufficiency, and for whom pre- and postoperative data were available, were studied for the purpose of determining the long term morphological functional results of the treatment. Almost all of the 43 patients (93.5%) had received a velopharyngeal flap graft according to Sanvenero-Rosselli. The remaining 4.7% had received a velopharyngeal adhesion according to Stellmach. Four physicians from the fields of oral surgery, orthodontics, phoniatrics, and logopedics evaluated the pre- and postoperative data as well as the results of the follow-up examination according to subjective criteria from their respective disciplines. All four physicians judged that following velopharyngeal flap graft a gradual improvement in the ability to speak had been achieved in 86% of the patients in the follow-up study. At the time of the follow-up examination 70% of these cases were judged to have achieved a "good" qualitative level of articulation and 21% were judged to have achieved a "usefull" level. The best results were obtained in patients who had been operated on before the age of six. The reason is that in these young patients muscular malfunction and pathological movement patterns can be more easily modified than in older patients. In many cases additional speech improvement was achieved through logopedic therapy following the velopharyngeal flap graft. In the most difficult cases intensive therapy while the patients were still hospitalized proved to be especially effective.(ABSTRACT TRUNCATED AT 250 WORDS)

Synthesis and characterization of a bioactive 82-residue sphingolipid activator protein, saposin C

The sphingolipid activator protein, saposin C (also termed SAP 2), was chemically synthesized, purified, and characterized. The fully protected 82-residue protein was synthesized by automated solid-phase methods, with multiple recoupling steps resulting in a high average coupling efficiency of 98.8%. The overall yield was estimated to be approx 40%. Deprotection and cleavage of the peptide from the resin was followed by folding in the absence of chaotropic agents at pH 8.5. The protein was purified by reversed-phase high pressure liquid chromatography (HPLC) and its purity determined by capillary electrophoresis and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The composition of the synthetic saposin C was determined by amino acid analysis. Its sequence was verified by Edman sequence analysis of overlapping peptide fragments generated by chymotryptic and Staphylococcus aureus V8 digestions. The sequence at the C-terminus was determined by digestion with carboxypeptidase P, followed by phenylthiohydantoin (PTH) derivitization and HPLC analysis of the released amino acid residues. Deglycosylated native saposin C appeared as a lower molecular-weight species than synthetic saposin C on SDS-PAGE. This has been explained by amino acid and C-terminal analysis showing native saposin C to be two amino acids shorter at the C terminus than a deduced sequence (from cDNA) previously published. Synthetic saposin C displayed 85% of full biological activity as determined by its ability to stimulate glucocerebrosidase activity in vitro: Synthetic and native saposin C increased glucocerebrosidase catalyzed hydrolysis of 4-methylumbelliferyl beta-D-glucoside by factors of 6.0 and 7.1, respectively. Furthermore, synthetic and native saposin C share similar K(act) values (0.5 and 1.5 microM respectively) indicating that they bind to glucocerebrosidase with similar affinities.

Characterization of human glucocerebrosidase from different mutant alleles

Human cDNA was mutagenized to duplicate six naturally occurring mutations in the gene for glucocere-brosidase. The mutant genes were expressed in NIH 3T3 cells. The abnormal human enzymes were purified by immunoaffinity chromatography and characterized. The Asn370----Ser mutant protein differed from normal enzyme in its inhibition by both conduritol B epoxide and glucosphingosine demonstrating that the 370 mutant enzyme has an abnormal catalytic site. In addition, the 370 mutant enzyme is less activated by saposin C, but more stimulated by phosphatidylserine than the wild type enzyme. The Arg463----Cys mutant protein was normal with respect to conduritol B epoxide and glucosphingosine inhibition, but was less activated by both saposin C and phosphatidylserine. The Arg120----Gln mutant protein was catalytically inactive. The Leu444----Pro, the pseudopattern, and the Pro415----Arg mutants appear to have reduced amounts of enzyme protein in cells. The studies demonstrated that mutations in the gene for glucocerebrosidase have different effects on the catalytic activity and stability of the enzyme.

Saposins (sphingolipid activator proteins) in the twitcher mutant mouse

The twitcher mutant mouse, the animal model of Krabbe disease (human globoid cell leukodystrophy), is characterized by apparent deficiency of galactosylceramide beta-galactosidase activity. Saposin A and C, the heat-stable small sphingolipid activator glycoproteins, stimulate the activity of galactosylceramide beta-galactosidase as well as glucosylceramide beta-glucoside. The role of these saposins in the twitcher mutation was investigated. Boiled supernatant fractions, which contained saposins, were prepared from homogenates of twitcher brain, liver, kidney, and spleen. These preparations showed an almost identical effect on the activity of purified glucosylceramide beta-glucosidase (measured by hydrolysis of 4-methylumbelliferyl-beta-glucoside) with similar preparations from control tissues. The effect on the activity of galactosylceramide beta-galactosidase as well as 4-methylumbelliferyl-beta-glucoside beta-glucosidase in the twitcher brain and liver homogenates by authentic saposin A and C was similar to that in control tissues. These results suggest that the twitcher mutation does not affect the concentrations of saposin A or C or their interaction with galactosylceramide beta-galactosidase.

Sequence of two alleles responsible for Gaucher disease

Enzymatically amplified RNA transcripts were used to analyze the full coding region of the glucocerebrosidase gene from Gaucher disease patients. Two previously undescribed mutations were identified. One mutation consists of a single-base substitution in three different codons: codon 444, Leu (CTG) to Pro (CCG); codon 456, Ala (GCT) to Pro (CCT); and codon 460, Val (GTG) to Val (GTC). This mutant is called "pseudo pattern" (psi) because it is identical in sequence to a small region of the pseudogene in exon 10 (Horowitz et al., 1989). The other new mutation is a single-base substitution (C to T) resulting in the substitution of Cys for Arg in codon 463. These mutations in the human gene were duplicated in wild-type cDNA and expressed in 3T3 cells. The human mutant proteins were isolated by immunoaffinity and shown to have altered enzymatic properties demonstrating the causality of these two allelic mutations for Gaucher disease.

Interaction of saposins, acidic lipids, and glucosylceramidase

Activity of lysosomal glucosylceramidase is stimulated by two small glycoproteins, saposin A and C, which are, together with two other similar glycoproteins, derived from a single precursor protein. This enzyme is also stimulated by naturally occurring acidic lipids, such as phosphatidylserine and gangliosides. Using highly purified glucosylceramidase, saposins, and acidic lipids, the mechanism of enzyme stimulation was studied by investigating complex formation between the three components and by examining effects on activity caused by changing amounts of saposins and acidic lipids, individually or in combination. The results indicated that acidic lipids form a water-soluble complex with glucosylceramidase but not with saposins and that saposins and acidic lipids each bind to the enzyme at two different sites for the activation. Based on these observations, the previously proposed three-binding sites model of glucosylceramidase, activator, and substrate was modified to one composed of four binding sites: one for carbohydrate of the substrate, one for aglycon, one for acidic lipids, and one for saposins.

The preparation of poly (dT)-5'-transferrin conjugates and hybridisation studies with poly (dA)-tailed linearised pBR322 plasmid DNA

The formation of transferrin-DNA complexes intended for ligand-directed transfection studies has been achieved through a hybridisation technique involving complementary homodeoxypolynucleotide chains attached to the participating protein and DNA species. Oligothymidylate residues (pT)n obtained by dicyclohexylcarbodiimide (CDI) polymerisation of thymidine-5'-monophosphate (5'-TMP) were activated to the 5'-imidazolides which on incubation with transferrin yielded the 5'linked phosphoramidates (pT)n-5'-transferrin. Homopolymeric chain extension of (pT)5-5'-transferrin by terminal transferase and dTTP at 30 degrees for 30 min yielded (pT) 300-5'-transferrin. Cleavage of the phosphoramide link in the polymer modified transferrin at 37 degrees was pronounced after 30 min although at 25 degrees hydrolysis was less than 5% after 4 hr. Poly(dT)-5'-transferrin readily hybridised with [3H]poly(dA)-tailed Pst 1 linearised pBR322 DNA. Resultant complexes were demonstrated by nitrocellulose filter binding and immunoprecipitation with anti-transferrin antibody. In contrast with poly(dT)-5'-transferrin, poly(dT)-5'-transferrin-poly(dA)-tailed pBR322 DNA complexes were stable at 37 degrees suggesting that annealing is followed by further stabilising interactions between the DNA and protein components.

Function of the adrenal cortex in patients with major depression

Failure to suppress cortisol secretion after administration of dexamethasone occurs in up to 50% of depressed patients. To test whether this hypothalamic-pituitary-adrenal (HPA) overactivity is associated with adrenocortical hyperresponsiveness, we performed dexamethasone suppression tests (DSTs) and adrenocorticotropic hormone (ACTH) stimulation tests in depressed subjects and subjects with other psychiatric disorders. Three groups were defined: depressed nonsuppressors, depressed suppressors, and other suppressors. While predexamethasone and postdexamethasone cortisol concentrations were greater in the depressed nonsuppressor group, ACTH concentrations did not differ among groups. After receiving alpha-ACTH[1-24] (4.2 micrograms/kg), depressed nonsuppressors had greater increases in stimulated cortisol secretion than the other groups. These results demonstrate that in a subgroup of depressed patients, HPA overactivity is associated with adrenocortical hyperresponsiveness.