POS0454 DIGITAL IMAGE ANALYSIS OF INTRAEPITHELIAL B-LYMPHOCYTES AS AN OBJECTIVE ALTERNATIVE TO ASSESS LYMPHOEPITHELIAL LESIONS IN SALIVARY GLANDS OF SJÖGREN’S SYNDROME PATIENTS

Background

Salivary glands of primary Sjögren’s syndrome (pSS) patients characteristically contain periductal lymphocytic infiltrates. Associated with these infiltrates, lymphoepithelial lesions (LELs) can be formed. LELs are composed of hyperplastic ductal epithelium with infiltrating lymphocytes and may assist in the diagnostic process of pSS1. However, manual identification of LELs on H&E staining is a subjective process and can be challenging. A more objective histological parameter that could assist in identification of LELs is the presence of intraepithelial lymphocytes within striated ducts, since we previously showed an association between intraepithelial B-lymphocytes and hyperplasia of the ductal epithelium2. These results, however, warrant validation in a larger cohort. Furthermore, associations between clinical parameters of pSS patients and presence of intraepithelial lymphocytes are not yet known.

Objectives

To investigate if detection of intraepithelial lymphocytes using digital image analysis can be used as an objective alternative to assess LELs, and to correlate presence of intraepithelial lymphocytes to clinical parameters of pSS patients.

Methods

Paired labial and parotid salivary gland biopsies of 109 patients clinically suspected for pSS were serially sectioned and stained for CD3 (T-lymphocytes), high molecular weight cytokeratin (striated ducts) and CD20 (B-lymphocytes). We developed a virtual triple staining digital image analysis (DIA) algorithm using the Visiopharm Integrator System (Visiopharm, Hørsholm, Denmark) to detect intraepithelial T- and B-lymphocytes within regions of interest comprising striated ducts. A maximum of 10 regions of interests was selected per biopsy. Presence of ductal hyperplasia was assessed on consecutive H&E stained slides. Patients were classified as pSS or non-SS according to the ACR-EULAR criteria.

Results

The DIA algorithm presented in this study was an accurate and objective method to detect intraepithelial lymphocytes within striated ducts in salivary gland tissue. Presence of intraepithelial B-lymphocytes, in contrast to intraepithelial T-lymphocytes, was a specific finding in salivary gland biopsies of pSS patients. In total, 59% of labial and 68% of parotid gland biopsies of pSS patients contained intraepithelial B-lymphocytes, against only 2% of patients classified as non-SS. Intraepithelial B-lymphocytes were not only detected within striated ducts with hyperplasia (LELs), but also in around 25% of analyzed striated ducts without hyperplasia of pSS patients (precursor stage of LEL). PSS patients with presence of intraepithelial B-lymphocytes in the labial gland showed lower stimulated whole salivary flow (p=0.011) and higher ocular staining scores (p=0.048), compared to patients without intraepithelial B-lymphocytes. Serological parameters, such as, rheumatoid factor-, IgG- and ESR levels were significantly higher in pSS patients with presence of B-lymphocyte containing ducts, irrespective whether the labial or parotid gland was taken into account.

Conclusion

Presence of B-lymphocyte containing ducts is a specific finding in salivary gland biopsies of pSS patients and is associated with clinical parameters of pSS. Together, identification of B-lymphocyte containing ducts by using DIA could be used as an objective marker in the diagnostic histopathological work-up of patients suspected of pSS.

References

[1]Ihrler S et al. Lymphoepithelial duct lesions in Sjogren-type sialadenitis. Virchows Archiv. 1999 Apr;434(4):315–23.

[2]Van Ginkel MS et al. Presence of intraepithelial B-lymphocytes is associated with the formation of lymphoepithelial lesions in salivary glands of primary Sjögren’s syndrome patients. Clinical and Experimental Rheumatology. 2019;37:S42–8.

Disclosure of Interests

Martha S. van Ginkel: None declared, Tineke van der Sluis: None declared, Marian L.C. Bulthuis: None declared, Henk J. Buikema: None declared, Erlin A. Haacke: None declared, Suzanne Arends: None declared, Stine Harder Employee of: SH is an employee of Visiopharm, Fred K.L. Spijkervet: None declared, Hendrika Bootsma: None declared, Arjan Vissink: None declared, Frans G.M. Kroese: None declared, Bert van der Vegt Consultant of: BvdV is on the scientific advisory board of Visiopharm, for which UMCG is compensated.

Strongly reducing magnesium(0) complexes

A complex of a metal in its zero oxidation state can be considered a stabilized, but highly reactive, form of a single metal atom. Such complexes are common for the more noble transition metals. Although rare examples are known for electronegative late-main-group p-block metals or semimetals^1-6, it is a challenge to isolate early-main-group s-block metals in their zero oxidation state^7-11. This is directly related to their very low electronegativity and strong tendency to oxidize. Here we present examples of zero-oxidation-state magnesium (that is, magnesium(0)) complexes that are stabilized by superbulky, monoanionic, β-diketiminate ligands. Whereas the reactivity of an organomagnesium compound is typically defined by the nucleophilicity of its organic groups and the electrophilicity of Mg²⁺ cations, the Mg⁰ complexes reported here feature electron-rich Mg centres that are nucleophilic and strongly reducing. The latter property is exemplified by the ability to reduce Na⁺ to Na⁰. We also present a complex with a linear Mg₃ core that formally could be described as a Mg^I-Mg⁰-Mg^I unit. Such multinuclear mixed-valence Mg_n clusters are discussed as fleeting intermediates during the early stages of Grignard reagent formation. Their remarkably strong reducing power implies a rich reactivity and application as specialized reducing agents.

Home visits in the Danish High Risk and Resilience Study - VIA 7: assessment of the home environment of 508 7-year-old children born to parents diagnosed with schizophrenia or bipolar disorder

OBJECTIVE

The home environment provided by the caregivers of a child is an influential single factor for development and well-being. We aimed to compare the quality of the home environment of children at familial high risk of schizophrenia or bipolar disorder with population-based controls.

METHODS

Danish nationwide registers were used to retrieve a cohort of 522 7-year-old children of parents diagnosed with schizophrenia (N = 202), bipolar disorder (N = 120) or none of these diagnoses (N = 200). The home environment was assessed using the Middle Childhood-Home Observation for Measurement of the Environment Inventory (MC-HOME Inventory).

RESULTS

The proportion of children living in home environments that were evaluated not to meet the needs of a 7-year-old child was significantly larger in the two familial high-risk groups. This was true for 21% of the children with familial predisposition for schizophrenia and 7% of children with familial disposition for bipolar disorder.

CONCLUSION

Children born to parents diagnosed with schizophrenia and to a lesser extent bipolar disorder are at an increased risk of growing up in a home environment with an insufficient level of stimulation and support. Identifying families with inadequate home environments is a necessary step towards specialized help and support to at-risk families.

Hair cortisol in the perinatal period mediates associations between maternal adversity and disrupted maternal interaction in early infancy

Existing literature points to the possibility that cortisol could be one link between maternal adversity and poorer parenting quality, but most studies have examined salivary cortisol concentrations rather than hair cortisol concentrations. The current study examined hair cortisol concentration (HCC) during the third trimester of pregnancy as a mediator between maternal adversity indicators (childhood abuse, severe mental illness, symptomatic functioning) and maternal caregiving behavior at 4 months postpartum. Forty-four women participated in the study: 30 with severe mental disorders, and 14 nonclinical controls. HCC was assessed during the third trimester of pregnancy (HCC-P) and at 4 months postpartum (HCC-4M). Sexual, physical, and emotional abuse were assessed by the Adverse Childhood Experiences Study Questionnaire. Maternal disrupted interaction was reliably coded from mother-infant video interactions during a Still-Face Procedure. Mediation models indicated that maternal HCC-P and HCC-4M mediated associations between maternal psychopathology (severe mental illness, symptomatic functioning) and maternal disrupted interaction at 4 months. Maternal HCC at 4 months also mediated associations between experienced childhood abuse and overall disrupted interaction. Our findings indicate that HCC may be a potential early biomarker for future caregiving challenges among mothers with severe mental illness and histories of childhood abuse.

Osseointegration of dental implants in ectopic engineered bone in three different scaffold materials

The in vivo regeneration of bone flaps might be an alternative to autogenous bone grafting. The first human case of mandibular reconstruction using the greater omentum as a bioreactor was reported in 2016. However, whether engineered bone will support the osseointegration of dental implants has not yet been investigated. In this study, bone tissue engineering was performed in the greater omentum of nine miniature pigs using bone morphogenetic protein 2, bone marrow aspirate, and three different scaffolds: hydroxyapatite, biphasic calcium phosphate (BCP), and titanium. After 8 weeks, two implants were placed in each scaffold; after another 8 weeks, the bone blocks were harvested for radiographic, histological, and histomorphometric analysis. All implants exhibited sufficient primary stability, and the success rate was 100%. The bone-to-implant contact ratios (BICs) were 38.2%, 68.5%, and 42.9%; the inter-thread bone densities were 29.4%, 64.9%, and 33.5%; and the peri-implant bone-scaffold densities were 56.4%, 87.6%, and 68.6% in the hydroxyapatite, BCP, and titanium groups, respectively. The BIC showed a strong correlation (r = 0.76) with the peri-implant bone-scaffold density. This study shows that de novo engineered bone leads to successful osseointegration and therefore may allow implant-based prosthodontic rehabilitation.

Gold complexes for focused-electron-beam-induced deposition

Four gold complexes were tested as a precursor for focused-electron-beam-induced deposition: [ClAu(III)Me2]2, ClAu(I)(SMe2), ClAu(I)(PMe3), and MeAu(I)(PMe3). Complexes [ClAu(III)Me2]2 and MeAu(I)(PMe3) are volatile, have sufficient vapor pressure at room temperature for deposition experiments, and were found to yield deposits that contain gold (29-41 and 19-25 atom %, respectively). Electrons easily remove the Cl ligand from [ClAu(III)Me2]2, and predominantly both methyl ligands are incorporated into the deposit. Electrons remove at least one methyl group from MeAu(I)(PMe3). Complexes ClAu(I)(SMe2) and ClAu(I)(PMe3) are not suitable as a precursor. They dissociate in vacuum, and the only volatile components are Cl, SMe2, and PMe3, respectively.

Comparative clinical effects of hydromorphone and morphine: a meta-analysis

We have conducted a meta-analysis of the clinical effects of morphine and hydromorphone to compare their benefit in analgesia. Embase and Medline were searched with an end-date of June 2009 for randomized, controlled trials or observational studies that addressed comparative analgesic and side-effects or particular side-effects. Two researchers independently identified included studies and extracted the data. Estimates of opioid effects were combined by using a random-effects model. Meta-analysis of eight studies suggested that hydromorphone (494 patients) provides slightly better (P=0.012) clinical analgesia than morphine (510 patients). The effect-size was small (Cohen's d=0.266) and disappeared when one study was removed, although the advantage of hydromorphone was more evident in studies of better quality (Jadad's rating). Side-effects were similar, for example, nausea (P=0.383, nine studies, 456 patients receiving hydromorphone and 460 morphine); vomiting (P=0.306, six studies, 246 patients receiving hydromorphone and 239 morphine); or itching (P=0.249, eight studies, 405 patients receiving hydromorphone, 410 morphine). This suggests some advantage of hydromorphone over morphine for analgesia. Additional potential clinical pharmacological advantages with regard to side-effects, such as safety in renal failure or during acute analgesia titration, are based on limited evidence and require substantiation by further studies.

Clinical and neuroimaging findings of Cree leukodystrophy: a retrospective case series

BACKGROUND AND PURPOSE

CLD is a rapidly progressive and invariably fatal neurodegenerative disorder. We describe clinical and neuroimaging findings in 5 infants with CLD.

MATERIALS AND METHODS

Retrospective review of medical records of infants with CLD from the past 11 years at our institution was performed. Relevant clinical and demographic data were recorded. Specific attention was directed toward postmortem examination findings and genetic testing. CT and MR imaging results were reviewed.

RESULTS

Five Cree infants were diagnosed with CLD. CT demonstrated bilateral symmetric hypoattenuation of the white matter and globus pallidus. MR imaging demonstrated corresponding T2 hyperintensity in these regions and abnormal signal intensity in the thalami and substantia nigra. Symmetric restricted diffusion in the deep white matter was seen. MRS demonstrated decreased NAA, elevated choline, and the presence of lactate. Postmortem examination in 1 infant showed corresponding poor myelination in the brain stem, cerebellum, deep gray structures, and the cerebral hemispheres. Genetic testing in 2 infants revealed homozygous mutations in the eIF2B5 gene.

CONCLUSIONS

Neuroimaging in CLD is striking and is an important tool in diagnosing CLD. Extensive white matter involvement as well as involvement of the globus pallidus and patchy involvement of the thalami and substantia nigra are characteristic. MRS findings are compatible with destruction of normal brain parenchyma with evidence of anaerobic metabolism in the regions of demyelination. Clinical suspicion of VWM in a Native American infant from this region should prompt the consideration of CLD with appropriate imaging work-up and genetic testing.

Argatroban for elective percutaneous coronary intervention: the ARG-E04 multi-center study

The synthetic arginine-derived direct thrombin inhibitor argatroban is an attractive anticoagulant for percutaneous coronary intervention (PCI), because of its rapid onset and offset, and its hepatic elimination. Argatroban was approved for PCI in patients with heparin-induced thrombocytopenia (HIT). However, there are limited data about argatroban in non-HIT patients. The objective of this open-label, multiple-dose, controlled study was to examine the safety and efficacy of argatroban in patients undergoing elective PCI.

METHODS AND RESULTS

Of 140 patients randomized to three argatroban dose groups (ARG250, ARG300, and ARG350 with 250, 300, or 350 μg/kg bolus, followed by 15, 20, or 25 μg/kg/min infusion) and one unfractionated heparin (UFH) group (70-100 IU/kg bolus), 138 patients were analyzed. Argatroban dose-dependently prolonged activated clotting time (ACT) with more patients reaching the minimum target ACT after the initial bolus injection (ARG250: 86.1%, ARG300: 89.5%, and ARG350: 96.8%) compared to 45.5% in UFH (p<0.001). The patient proportion who did not require additional bolus injections to start PCI was significantly higher in argatroban than in UFH (p ≤ 0.002). Consequently, the time to start of PCI was shortened in argatroban groups. Composite incidences of death, myocardial infarction, and urgent revascularization until day 30 were not significantly different between the groups (ARG250: 2.8%, ARG300: 0.0%, ARG350: 3.2% vs. UFH: 3.0%). Major bleeding was observed only in UFH (3.0%), while minor bleeding occurred in ARG350 (3.2%) and UFH (6.1%, n.s.).

CONCLUSION

Argatroban dose-dependently increases coagulation parameters and, compared to UFH, demonstrates a superior predictable anticoagulant effect in patients undergoing elective PCI.

Long term administration of LMWH - pharmacodynamic parameters under therapeutic or prophylactic regimen of enoxaparin or tinzaparin in neurological rehabilitation patients

We investigated anti-FXa- and anti-FIIa-activity, thrombin generation (ETP), tissue factor pathway inhibitor (TFPI) - and D-dimer in patients exhibiting high bleeding risk in early neurological rehabilitation over 2 months in an observational study. Blood of 64 patients under LMWH administration due to therapeutic (cohort 1 [tinzaparin 90 IE/kg BID, N = 18] and 2 [enoxaparin 100 IE/kg BID; N = 15]) or prophylactic (cohort 3 [tinzaparin 4500 IE; N = 16] and 4 [enoxaparin 4000 IE; N = 15]) indication was drawn before and 4h after injection on day 7 (V1) and 2 months (follow up [V2]). Although the dose in cohort 1 and 2 was similar (median 7000 IE BID), a-FXa-activity was significantly larger under enoxaparin than under tinzaparin (e.g. median at V2: 0.70 IU/ml vs. 0.33 IU/ml). Also, prophylactic enoxaparin exhibited larger a-FXa-activity than tinzaparin (e.g. median at V2: 0.37 IU/ml vs. 0.22 IU/ml). The a-FXa/a-FIIa-ratio in plasma samples at 4h p.a. was about 4 (tinzaparin) and 8 (enoxaparin), respectively. No differences were seen for TFPI and ETP between cohort 1 and 2 or between cohort 3 and 4. D-dimer levels decreased significantly between V1 (e.g. cohort 4 median 1940 ng/ml) and V2 (median 652 ng/ml). Minimal bleeding events occurred in 6 patients (2 under tinzaparin, 4 under enoxaparin) and were associated with significantly higher anti-FXa-activity. In conclusion, although marked differences between tinzaparin and enoxaparin based on anti-FXa-activity were seen, markers of in vivo biological activity such as TFPI and D-dimer were not different. Furthermore, BID tinzaparin is a feasible option for therapeutic anticoagulation in patients with high bleeding risk.

Platelet-dependent thrombin generation assay for monitoring the efficacy of recombinant Factor VIIa

Although the administration of recombinant coagulation factor VIIa (rFVIIa) is a well established treatment in haemophilia with inhibitory antibodies, monitoring the therapeutic efficacy is still a problem. This is because the complete haemostatic effect in vivo depends on negatively charged surfaces provided by exposed lipids from activated platelets which are not present in standard clinical assays using plasma. The thrombin generation assay, however, measures the endogenous thrombin potential (ETP) in platelet-rich plasma (PRP) and this assay might be useful for monitoring the haemostatic response to rFVIIa. We characterized the in vitro concentration-response relationship of rFVIIa and the thrombin generation parameters ETP, PEAK and TIME TO PEAK using platelet-rich plasma (PRP) and rFVIIa at concentrations between one and five times the therapeutic dose. We also studied the effect of inhibiting tissue-factor and the intrinsic coagulation pathway using excess TF-neutralizing antibodies and corn trypsin inhibitor (CTI), respectively. There was a sigmoid relationship between ETP and PEAK and the dose of rFVIIa. Increasing rFVIIa concentrations between 100 and 500 U/ml resulted in a progressive increase in ETP, whereas supratherapeutical concentrations led to a plateau phase. The plateau phase differed between patients, suggesting a biological variation in the maximum ETP. Neutralization of plasma TF with TF-Ab partially decreased FVIIa efficacy. The inhibitory effect of CTI on rFVIIa-induced thrombin generation via the intrinsic pathway was negligible. The thrombin generation assay using PRP is a useful test for determining the sufficient efficacy of rFVIIa in blood. Once a plateau level is reached, higher doses of rFVIIa have no additional effect on haemostatic efficacy. The variation in plateau levels between subjects indicates that there are inter-individual differences in the level of thrombin activity that can be generated. High doses of rFVIIa are effective even in the absence of TF.

Effects of selective COX-2 inhibition on prostanoids and platelet physiology in young healthy volunteers

BACKGROUND

Selective inhibitors of cyclooxygenase-2 (COX-2) called coxibs, are effective anti-inflammatory and analgesic drugs. Recently, these drugs were associated with an increased risk for myocardial infarction and atherothrombotic events. The hypothesis of thromboxane-prostacyclin imbalance has been preferred to explain these unwanted effects.

METHODS

We studied the effects of 14 days intake of rofecoxib (25 mg q.d.), celecoxib (200 mg b.i.d.), naproxen (500 mg b.i.d.) and placebo in a randomized, blinded, placebo-controlled study in young healthy volunteers (median age 25-30 years, each group n = 10). We assessed prostanoid metabolite excretion (PGE-M, TXB(2), 6-keto-PGF(1alpha), 11-dehydro-TXB(2), 2,3-dinor-TXB(2), and dinor-6-keto-PGF(1alpha)), the expression of platelet activation markers (CD62P, PAC-1, fibrinogen), platelet-leukocyte formation, the endogenous thrombin potential, platelet cAMP content and plasma thrombomodulin level.

RESULTS

Naproxen suppressed biosynthesis of PGE-M, prostacyclin metabolites and thromboxane metabolites and thrombomodulin levels. In contrast, both coxibs had an inhibitory effect only on PGE-M, 6-keto-PGF(1alpha), and on dinor-6-keto-PGF(1alpha), whereas TXB(2), 2,3-dinor-TXB(2) and 11-dehydro-TXB(2) excretion were unaffected. None of the coxibs exerted significant effects on the expression of platelet activation markers, cAMP generation, platelet-leukocyte formation, or on thrombomodulin plasma levels. Interestingly, platelet TXB(2) release during aggregation was enhanced after coxib treatment following arachidonic acid or collagen stimulation.

CONCLUSION

In young healthy volunteers coxibs inhibit systemic PGE(2) and PGI(2) synthesis. Platelet function and expression of platelet aggregation markers are not affected; however, coxibs can stimulate TXB(2) release from activated platelets. Combined decrease in vasodilatory PGE(2) and PGI(2) together with increased TXA(2) in proaggregatory conditions may contribute to coxib side effects.

Monitoring effects of direct FXa-inhibitors with a new one-step prothrombinase-induced clotting time (PiCT) assay: comparative in vitro investigation with heparin, enoxaparin, fondaparinux and DX 9065a

Selective, direct factor Xa-inhibitors are an emerging new class of antithrombotic drugs but their application in therapy may require adequate laboratory monitoring. A recently introduced assay for monitoring anti-FXa-activity using Russell's viper venom is based on the prothrombinase-induced clotting time (PiCT). In this study comparative data on the performance of PiCT using direct and indirect FXa-inhibitors and measurements of FXa-activity and aPTT are reported.

METHODS

Whole citrated blood samples from six healthy volunteers were preincubated with UFH (0-1.0 IU/ml), enoxaparin (0-10 microg/ml), fondaparinux (0-1.0 microg/ ml) and DX 9065a (0-10 microg/ml). PTT, FXa-activity and PiCT in plasma were determined on an ACL coagulation analyzer. PiCT was done with both a 180-sec incubation period before recalcification (2-step), and without (1-step). FXa-activity was based on a chromogenic assay (S2222).

RESULTS

FXa-activity was reduced 10-40% by the lowest concentration and by 80-95% by the highest concentration of all agents. At the highest concentration the maximum prolongation in aPTT exceeded 120 sec with UFH, enoxaparin and DX 9065a but was only marginally prolonged (increase 39 +/- 3 sec) by fondaparinux. Prolongation in PiCT was significantly different when the two PiCT-methods were compared e.g. at 1.0 IU/ml UFH, 137 +/- 25 (1-step) vs. 187 +/- 32 sec (2-step) (p < 0.001); at 10 microg/ml enoxaparin 83 +/- 9 sec vs. 130 +/- 15 (p < 0.001); at 1.0 microg/ml fondaparinux 48 +/- 5 sec vs. 73 +/- 9 sec (p < 0.001); at 10 microg/ml DX 9065a 28 +/- 3 vs. 25 +/- 2 (p < 0.01), respectively. The 2-step method was unable to detect a prolongation in the effects of DX 9065a, and at concentrations < 5 microg/ml clotting times were even shorter (e.g. 13 +/- 1 sec at 1.0 microg/ml DX 9065a) than the baseline readings (20 +/- 2 sec).

CONCLUSIONS

Only the 1-step method (i.e. without pre-incubation) seems suitable for the monitoring of new, direct selective FXa-inhibitors.

Pharmacokinetics and tolerability of a combination of indinavir, lopinavir and ritonavir in multiply pretreated HIV-1 infected adults

OBJECTIVES

The authors evaluated the pharmacokinetics and tolerability of indinavir/lopinavir/ritonavir in a protease inhibitor only combination.

METHODS

Plasma drug levels of patients taking indinavir/lopinavir/ritonavir 800/400/100mg twice daily (n = 24, group 1) were compared to patients taking either lopinavir/ritonavir 400/100mg (n = 35, group2) or indinavir/ritonavir 800/100mg (n = 33, group3) twice daily plus nucleos(t)ide reverse transcriptase inhibitors (NRTI). Steady-state drug concentrations were measured by LC/MS/MS. Minimum and maximum concentrations (C subsetmin, C subsetmax), area under the concentration-time curve (AUC subset0-12h), total clearance (CL subsettot) and half-life (t1/2) were calculated. HIV viral load, CD4 cell count and adverse events causing early termination of therapy were correlated over a period of 48 weeks.

RESULTS

Plasma levels of lopinavir/ritonavir were significantly enhanced when combined with indinavir compared to a regimen of lopinavir/ritonavir+NRTI: Mean lopinavir AUC subset(0-12h) 80,912 ng*h/mL vs. 60,548 ng*h/mL; C subsetmin 4,633 ng/mL vs. 3,258 ng/mL; C subsetmax 8,023 ng/mL vs. 6,710 ng/mL. Mean ritonavir AUC(0-12h) 6,907 ng*h/mL vs. 3,467 ng*h/mL; Cmin 220 ng/mL vs. 125 ng/mL; C subsetmax 1,059 ng/mL vs. 522 ng/mL. Indinavir levels were comparable for both indinavir containing regimen. A significantly smaller number of patients stopped indinavir/lopinavir/ritonavir therapy (group1: 16.7%) than indinavir/ritonavir + NRTI treatment (group3: 45.5%) due to adverse events. Virological failure was the main reason for early termination of treatment with indinavir/lopinavir/ ritonavir before week 48 (group1: 50%).

CONCLUSIONS

indinavir/lopinavir/ritonavir 800/400/ 100mg twice daily represents a therapy option with an adequate safety but only short term efficacy for extensively pretreated patients.

The Retention Index Test Homburg (RTH-II): Response to clopidogrel and comparison with aggregometry and CD62P-expression

The Retention Index Test Homburg (RTH-II) is quoted to detect effects of shear stress on platelets, which involve ADP receptor signaling. RTH-II might be a tool for monitoring antiplatelet therapy for compounds that interfere with ADP induced platelet activation and secretion. In a series of investigations, we used an ADP (2 microM) triggered RTH-II in parallel with light-transmittance aggregometry and flow cytometry in subjects before and after clopidogrel. A loading dose of 225 mg clopidogrel leads to a significant reduction (p < 0.01) in the ADP-stimulated retention index (RI) from 69 +/- 15 to 48 +/- 21%, in the aggregation response to 5 microM ADP (from 50 +/- 20 to 29 +/- 21%) and the expression of CD62P (from 64 +/- 11 to 41 +/- 17%). Correlation analysis showed that the RI corresponds significantly to CD62P-expression (p < 0.01) but not to aggregation. We also found a strong correlation (p < 0.01) between the ADP-stimulated RI and the expression of CD62P after stimulation with 2 microM ADP, whereas no correlation was seen for RI vs. binding of PAC-1 or aggregation. Platelets not retained in the filter had lower CD62P expression than measured in the sample before the filter passage (54 vs. 35%). A direct interaction of CD62P with platelet ligands might lead to enhanced retention in RTH and explain the correlation of RI with CD62P expression. The RTH-II might be a simple and easy to handle platelet function assay for monitoring effects on P2Y(12)-inhibitors on platelet degranulation, perhaps in addition to aggregometry.

P-selectin (CD62p) and P-selectin glycoprotein ligand-1 (PSGL-1) polymorphisms: minor phenotypic differences in the formation of platelet-leukocyte aggregates and response to clopidogrel

INTRODUCTION

Formation of platelet-leukocyte aggregates (PLA) via the CD62p-ligand PSGL-1 represents an important mechanism by which leukocytes contribute to thrombotic and inflammatory events. Deficient variants (namely the Thr715Pro-SNP for CD62p and a VNTR-polymorphism for PSGL-1) might affect PLA formation and probably the response to clopidogrel (which is known to reduce PLA-formation).

METHODS

CD62p-expression, PLA-formation and the up-regulation of CD11b before (V1) and 24 hours after (V2) a loading dose of clopidogrel 225 mg were investigated in ten wild-type controls, ten heterozygote carriers of the Thr715Pro-allele and five carriers of the rare PSGL-1 B-allele (2 A/B and 3 B/B).

RESULTS

CD62p-expression before application of clopidogrel and under clopidogrel treatment in Pro715-haplotype samples did not differ from that in wild-type subjects. The response to clopidogrel was similar in all subjects. Pro715-carriers exhibited a significantly lower percentage of monocytes with platelets attached prior to clopidogrel treatment (ADP: median 22 (1st-3rd quartile 20-23), TRAP: 27 (25 - 38)) compared to the wild-type (ADP: 37 (31-44), TRAP: 55 (37-63)). These differences were not present under clopidogrel, and CD11b-expression was significantly reduced in both groups (controls: median 150 (quartile range 121 - 230) to 113 (121 - 230), Pro715-carriers: 147 (139 - 221) to 126 (109 - 170); all values refer to mean fluorescence intensity). Statistical analysis was not done in the case of PSGL-1 B-allele carriers, but PLA-formation before and under clopidogrel was always at the bottom end of the range seen in the control group and the Pro715-carriers or even below this range.

CONCLUSION

Minor phenotypic differences in the CD62p-PSGL-1 axis could be demonstrated in this study. Carriers of these polymorphisms showed a full response to clopidogrel comparable to that in control subjects.

Myelodysplastic syndrome of donor origin subsequent to successful treatment of myeloid/NK-cell precursor leukaemia with allogeneic PBSCT: two very rare conditions in one patient

We report a 36-year-old male with myeloid/natural killer (NK)-cell precursor acute leukaemia with a complex aberrant karyotype, who was treated according to an acute-myeloid-leukaemia (AML) treatment protocol (idarubicine, cytarabine, and etoposide) followed by high-dose cytarabine consolidation and achieved complete remission. He underwent allogeneic matched unrelated donor (MUD) peripheral blood stem-cell transplantation (PBSCT) and remained in remission throughout his remaining life. Seven months posttransplantation, a myelodysplastic syndrome (MDS) with (20q-) of donor origin was diagnosed causing severe thrombocytopenia and finally leading to infection and death. This patient represents one of the few cases published achieving remission for a significant period of time after being diagnosed with myeloid/NK-cell precursor acute leukaemia, a very rare malignant disease. We conclude, despite the fatal outcome due to infection, that allogeneic PBSCT is a therapeutic option for patients with this entity. In addition, the development of a myelodysplastic syndrome of donor origin is extremely rare and only very few cases are published worldwide.

[The value of platelet function tests]

Platelet function tests are used to detect patients with abnormal platelet function, which may be inborn or acquired or to detect increased platelet activation which may be accompanied by an increased risk of thrombosis. Platelet function tests are also used to monitor platelet function inhibitors as aspirin, clopidogrel or platelet membrane glycoprotein IIb/IIIa-inhibitors. Incorrect blood sampling is a major source of error in measuring platelet function. Global tests besides platelet count and bleeding time are thrombelastography, the platelet function analyzer (PFA) and possibly in the future the new Impact-system. Specific tests measure platelet spreading and adhesion to defined surfaces. In a series of methods platelets are counted before and after passage of a filter. Some of these tests are partially standardized. The most frequently measured platelet function is aggregation induced by ADP, collagen or other substances as first described by Gustav Born. Some newer methods to perform aggregometry are described. Platelet activation can be detected by measuring spontaneous aggregation as in the PAT-test. Prospective trials with this test have shown that enhanced spontaneous aggregation is a risk factor for new vascular occlusions in diabetics and for myocardial infarctions in healthy individuals. The Wu and Hoak-test and the measurement of released platelet factor 4 or betaglobulin are of limited value. Flow cytometric methods are frequently used to measure platelet activation markers as CD 62 and others. Platelet induced thrombin generation is an interesting function to measure drug effects. None of the presently available platelet function tests is well standardized, so there is much room for improvement.

Oculoleptomeningeal amyloidosis in a large kindred with a new transthyretin variant Tyr69His

OBJECTIVE

To describe the clinical, radiologic, and pathologic findings of a kindred with oculoleptomeningeal amyloidosis and a newly associated transthyretin mutation.

BACKGROUND

Transthyretin (TTR) amyloidosis can present in the form of oculoleptomeningeal amyloidosis. Clinical features include dementia, seizures, stroke-like episodes, subarachnoid hemorrhage, ataxia, myelopathy, deafness, radiculopathy, and ocular amyloidosis. Eight TTR mutations associated with oculoleptomeningeal amyloidosis have been described.

METHODS

Fourteen individuals from a kindred with oculoleptomeningeal amyloidosis were examined clinically and radiologically. Analysis of the TTR gene was performed. Neuropathologic examination was obtained on the index patient.

RESULTS

Affected individuals had vitreous amyloid, radiculopathy, seizures, stroke-like episodes, encephalopathy, and dementia. Severely affected individuals died by the end of the fifth decade. Leptomeningeal enhancement on contrast MRI and elevated CSF protein were the defining features on investigations. Sequencing of exon 3 in the TTR gene found a base pair substitution at codon 69. This resulted in heterozygosity for normal tyrosine and variant histidine (ATTR Tyr69His) in affected family members. Domino liver transplantation was attempted as treatment for one family member.

CONCLUSIONS

The ATTR Tyr69His mutation is associated with oculoleptomeningeal amyloidosis. Expression of the genotype is variable. This has implications for treatment of affected individuals and counseling of family members. Efficacy of liver transplantation in patients with oculoleptomeningeal amyloidosis remains unknown. The authors advocate the investigation of liver transplantation in patients with severe symptoms due to oculoleptomeningeal amyloidosis.

Pharmacokinetics of pravastatin in heart-transplant patients taking cyclosporin A

BACKGROUND

Heart transplantation is an established tool for the treatment of terminal heart failure. Hyperlipidemia is a common problem following heart transplantation and has been implicated as an additional risk factor in the development of transplant coronary artery disease (TxCAD). Therefore, heart recipients are commonly treated with inhibitors of cholesterol synthesis (HMG-CoA reductase inhibitors). However, these patients have an increased risk of developing rhabdomyolysis due to elevated concentrations of HMG-CoA reductase inhibitors under co-administration with the immunosuppressive cyclosporin A (CsA).

AIM OF THE STUDY

Aim of our study was to obtain pharmacokinetic data on pravastatin whilst monitoring the safety and efficiency of the lipid lowering therapy in heart-transplant recipients under immunosuppression with CsA and to compare these data to those of a healthy control group.

SUBJECTS, MATERIALS AND METHODS

Eleven patients (30.2 +/- 12.3 months after transplantation) receiving immunosuppressive therapy consisting of cyclosporin A, prednisone and azathioprine with LDL cholesterol (LDL-C) concentrations exceeding 3.9 mmol/l and 8 control subjects were included into the study. In addition to the immunosuppressive therapy, the patients received a daily dose of 40 mg/day pravastatin for the first 8 days which was then reduced to 10 mg/day administered until Day 29. Blood was sampled for pharmacokinetic profiling (maximum concentration of the drug (Cmax), time to reach Cmax (tmax), area under the concentration vs. time curve (AUC(0-24h)), elimination half-life time (tcl)) and measurement of the parameters of clinical chemistry on Days 1, 8 and 29. The control group received a single dose of 60 mg pravastatin and the values of Cmax and AUC(0-24h) were normalized for a dose of 10 mg.

RESULTS

Pravastatin 40 mg/day for 1 week in the patient group caused a significant reduction in total cholesterol (C) and LDL-C from 8.11 +/- 1.20 mmol/l and 5.88 +/- 1.15 mmol/l to 6.91 +/- 1.01 mmol/l and 4.72 +/- 1.05 mmol/l, respectively (p = 0.005 and p = 0.003). Triglycerides and HDL cholesterol (HDL-C) concentrations did not change significantly. Mean values for Cmax of pravastatin were 384.2 ng/ml, 392.0 ng/ml and 115.1 ng/ml in patients on Days 1, 8 and 29, respectively. After normalization for a dose of 10 mg, the corresponding values of C(max-DN10mg) and Cmax were 96.0 ng/ml, 98.0 ng/ml and 115.1 ng/ml on study Days 1, 8 and 29. These values were 7-8 times higher than the normalized value of C(max-DN10mg) for the control group (13.7 ng/ml). The corresponding values of AUC(0-24h) were 1228.2 ng/ml x h, 1214.1 ng/ml x h and 345.9 ng/ml x h in the patient group on study Days 1, 8 and 29 as well as 157.5 ng/ml x h in the control group prior to normalization. After normalization for a dose of 10 mg, the values of AUC(0-24h-DN10mg) in the patient group were approximately 12 times higher than those of the control group. However, no significant differences between the 2 groups were observed in tmax and tcl. Within the patient group, no significant increase in Cmax or AUC was found on Day 1 to Day 8. The results of creatine kinase (CK), lactate dehydrogenase (LDH), aspartate aminotransferase (ASAT) and alanine aminotransferase (ALAT) showed also no significant increase during the observation period.

CONCLUSION

Heart-transplant recipients treated with the HMG-CoA reductase inhibitor pravastatin generally show higher plasma concentrations of this drug than control subjects. However, our data suggest that the HMG-CoA reductase inhibitor pravastatin can be used effectively in these patients receiving the immunosuppressive cyclosporin A. The pharmacokinetic data obtained indicate that there is no significant cumulation of the drug following multiple dosages in spite of increased drug concentrations after a single oral dosage.

Effects of antiplatelet agents on platelet-induced thrombin generation

OBJECTIVES

The influence of antiplatelet agents on platelet-induced thrombin generation may increase the risk of bleeding. Assessment of the endogenous thrombin potential (ETP), is therefore a parameter deserving attention in early pharmacodynamic studies with antiplatelet drugs. The aim ofthis study was to assess whether an automated ETP-assay can be used to determine possible inhibitory effects of antiplatelet drugs on platelet-associated thrombin generation.

METHODS

We first characterized the in vitro dose-response relationship of several platelet agonists (ADP, collagen, U46619, TRAP (amino acid sequence: SFLLRNP) and tissue factor (TF) using the generation of ETP. One submaximal concentration of each agonist was then used to assess the influence of in vivo treatment with aspirin (single oral dose of 500 mg as inhibitor of thromboxane synthesis) and clopidogrel (given orally for 6 days, as an inhibitor of the purinergic P2Y12-receptor on platelets) and in vitro treatment with abciximab (which inhibits the platelet glycoprotein IIb/IIIa-receptor for fibrinogen), on the ETP.

RESULTS

The effect of TF and the other platelet inducers on thrombin generation was dose-dependent. Repeat measurements on samples from the same subject, with the same inducer concentration on 2 different occasions showed a variability of approx. 22% (absolute difference between 2 measurements as % of mean). The coefficient on variation of repeat measurements of one sample varied between 7% and 17%, depending on the inducer. After a single dose of aspirin, ETP was reduced by 25-40%, depending on the platelet activating agent used. The reduction in ETP with abciximab in vitro was more pronounced. In contrast, TF-induced ETP was not influenced by aspirin or abciximab. Clopidogrel, administered for 6 days, reduced the ETP by 60% when platelets were stimulated using 20 microM ADP, whereas collagen-induced ETP and TF-induced ETP remained unchanged.

CONCLUSIONS

The ETP-method is a sensitive and reproducible method for the detection of drug effects on platelet-induced thrombin generation of high throughput, and can be recommended for studies on the pharmacodynamic profile of drugs interfering with platelet function.

Lipid-lowering treatment in coronary artery disease: a survey in an ambulatory outpatient clinic

OBJECTIVES

In controlled trials, HMG-CoA reductase inhibitors (statins) effectively reduced cardiovascular events in patients with coronary artery disease (CAD). However, recent pharmacoepidemiological studies indicate an underuse of statins in the target population. The objective of this study was to examine the extent to which CAD patients in Germany actually received statins under field conditions.

METHODS

We evaluated the medical records of 296 patients referred to the cardiology outpatient clinic of the Frankfurt University Hospital by their general practitioner (GP) in the period 1995 to 1998. All patients had symptomatic, angiographically proven CAD, 142 had previous myocardial infarction. A diagnosis of dyslipidemia was taken from the records. Most patients were visited on more than 1 occasion. In all, we were able to access 296 records for a 1st visit, 76 records for a 2nd visit and 29 records for a 3rd visit and 16 records for > 3 visits.

RESULTS

According to the entry criteria of the 4S Trial (total cholesterol 5.5-8.0 mmol/l or 212-311 mg/dl), 108 patients were deemed as eligible for lipid-lowering treatment, criteria of the LIPID Trial (4.0-7.0 mmol/l or 154-270 mg/dl) gave a yield of 190 patients. The actual treatment rate with a statin at the 1st visit was 34% (LIPID Group) and 40% (4S Group). At later visits, the treatment rates with statins increased to 63% (LIPID Group) and 79% (4S Group), due to advice given to the GP by the outpatient clinic. When the observation period was devided into 2 periods (04/95 - 01/97; 02/97 - 09/98), actual treatment rates (all visits) for the 4S Group were 43% and 38%, respectively, indicating no further "penetration" of the 4S Study in the therapy decision-making of the GPs.

CONCLUSIONS

The data indicate that necessary treatment with a HMG-CoA reductase inhibitor is often withheld in the ambulatory setting.

Pharmacokinetic-pharmacodynamic relationship of levodopa with and without tolcapone in patients with Parkinson's disease

OBJECTIVE

To investigate the effect of administration of the catechol-Omethyltransferase (COMT) inhibitor tolcapone on the concentration-effect relationship of levodopa in patients with advanced Parkinson's disease and on-off fluctuations.

DESIGN

Nonblind single-group 2-period pharmacokinetic-pharmacodynamic study.

PATIENTS AND PARTICIPANTS

12 patients, mean age 59 years, with idiopathic Parkinson's disease and response fluctuations.

METHODS

The pharmacokinetics [plasma concentrations of levodopa and 3-O-methyldopa (3-OMD)] and motor effects [global score of the Columbia University Rating Scale (CURSsigma)] of levodopa (plus the peripheral decarboxylase inhibitor benserazide 1:4) were determined for 4 consecutive dosage intervals (4 hours each, starting at 8.00am) in 12 patients before (day 1) and during (day 8) coadministration of tolcapone 100 mg 3 times daily for 7 days.

RESULTS

Under tolcapone, exposure to levodopa [area under the plasma concentration-time for the dosage interval (AUCt)] observed for the separate doses increased by 1.6- to 2.2-fold, and peak plasma drug concentrations (Cmax) increased by 1.1 - to 2.1 -fold. 3-OMD concentrations at day 8 were reduced to about 20% of the values at day 1. At baseline (day 1, before the first levodopa dose), CURSsigma averaged 40 +/- 10 points. After the first levodopa dose. CURSsigma declined to 20 +/- 9 points. At day 8. the predose CURSsigma decreased to a final score of 31 +/-13 points, and the maximal decline after the first levodopa dose was to a final score of 16 +/- 8 points. Population analysis (NONMEM) of the concentration-effect relationship of levodopa according to a sigmoidal Emax model and over all dosage intervals did not show differences in levodopa responsiveness with or without tolcapone. The population mean of the 50% effective concentration (EC50) of levodopa was 1350 microg/L with an standard error of the population parameter estimate of 18%: adding tolcapone treatment as a covariate did not significantly change the population fit. Circadian influences on levodopa respon- siveness were not evaluable by the NONMEM model due to overparametrisation, but visual inspection of plotted data did not suggest differences in the concentration-effect relationship between the 4 consecutive dosage intervals on days 1 and 8.

CONCLUSIONS

The gain in clinical improvement with levodopa under tolcapone can be fully explained by tolcapone-induced changes of peripheral levodopa pharmacokinetics. We suggest that this interaction study, performed in patients and using clinical data, excludes any central effects of tolcapone or any inhibiting effect of 3-OMD on levodopa permeation through the blood-brain barrier, which otherwise would have led to a decrease in the EC50 of levodopa.

Cloning of two thyrotropin-releasing hormone receptor subtypes from a lower vertebrate (Catostomus commersoni): functional expression, gene structure, and evolution

A PCR approach was used to clone thyrotropin-releasing hormone receptors (TRH-R) from the brain and anterior pituitary of the teleost Catostomus commersoni (cc), the white sucker. Two distinct TRH-R, designated ccTRH-R1 and ccTRH-R2, were identified. ccTRH-R1 was similar to mammalian TRH-R of the subtype 1, whereas ccTRH-R2 exhibited the highest identity (61% at the amino acid level) with the recently discovered rat TRH-R2. It is postulated that ccTRH-R2 and rat TRH-R2 are members of the same TRH-R subfamily 2. Functional expression of ccTRH receptors in human embryonic kidney cells and in Xenopus laevis oocytes demonstrated that both ccTRH receptors were fully functional in both systems. Oocytes expressing either receptor responded to the application of TRH by an induction of membrane chloride currents, indicating that ccTRH-R of both subtypes are coupled to the inositol phosphate/calcium pathway. The analysis of genomic clones revealed, for the first time, both similarities and differences in the structure of TRH-R subtype genes. Both ccTRH-R genes contained an intron within the coding region at the beginning of transmembrane domain (TM) 6. The position of this intron is highly conserved, as it was found at an identical position in the human TRH-R1 gene. The ccTRH-R2 gene contained an additional intron at the end of TM 3 that was not found in any of the TRH-R1 genes identified so far. The analysis of the gene structure of ccTRH-R and the amino acid sequence comparisons of mammalian and teleost TRH-R of both subtypes suggest that TRH receptors have been highly conserved during the course of vertebrate evolution. A common ancestral TRH receptor gene that could be found much earlier in evolution, possibly in invertebrates, might be the origin of ccTRH-R genes.

Levodopa pharmacokinetic-pharmacodynamic modeling and 6-[18F]levodopa positron emission tomography in patients with Parkinson's disease

OBJECTIVE

Parameters of a pharmacokinetic-pharmacodynamic (PK-PD) model of levodopa have been claimed to reflect the magnitude of the dopaminergic deficit in patients with Parkinson's disease. The aim of this study was to correlate such parameters with positron emission tomography (PET) with levodopa tagged with 6-fluorine 18, an established imaging method for striatal dopaminergic neurons.

METHODS

Twenty-three patients in different disease stages (Hoehm and Yahr stage 2.5-5 [Hoehn MM, Yahr MD. Parkinsonism: onset, progression and mortality. Neurology 1967;4:427-42]; median duration, 12 years) were studied. PK-PD modeling followed a single oral dose of levodopa/benserazide. The sum score of the Columbia Rating Scale (CURSSigma) was used for clinical assessments. A nonparametric effect compartment approach assuming a sigmoidal E(max) model was applied to the PK-PD analysis of plasma levodopa concentrations and corresponding CURSSigma. Thereafter 6-[18F]levodopa PET was performed, and the influx rate constants (k(c)) for the putamen and the caudatus region were correlated with the median effective concentration (EC(50)) and the equilibrium half-life (T(eq)) of the PK-PD model.

RESULTS

(1) A significant correlation was observed between PK-PD parameters or with k(c) putamen as the dependent variable and the duration of the disease as the independent variable, which explains 33% of the variability of the EC(50), 42% of the variability of T(eq), and 36% of the variability of k(c). (2) Significant correlations were observed between k(c) and either EC(50) or T(eq), yielding the closest correlation for the putamen region (r = -0.47, P <.05; and r = 0.55, P <.01; respectively).

CONCLUSIONS

Our findings show that key parameters of a PK-PD model of levodopa were in fairly close agreement with imaging of dopaminergic neurons by 6-[18F]levodopa PET. However, although PK-PD modeling of levodopa has been proven as a useful investigation of approaches aimed to restore dopaminergic deficits or to monitor disease progression, this modeling cannot serve as a pathomorphologic surrogate for the loss of striatal dopaminergic neurons.

Angiotensin II infusion increases plasma erythropoietin levels via an angiotensin II type 1 receptor-dependent pathway

BACKGROUND

Angiotensin-converting enzyme inhibitors (ACEIs) have been shown to lower hematocrit and erythropoietin (EPO), but a direct link between angiotensin II (Ang II) and EPO in humans has not been shown.

METHODS

Placebo or Ang II was infused for six hours in nine healthy male volunteers with and without blockade of the Ang II subtype 1 receptor (AT1R). EPO concentrations were measured 3, 6, 12, and 24 hours after the start of the infusion.

RESULTS

Ang II raised the mean arterial pressure by about 20 mm Hg. Consistent with the known diurnal variation, EPO levels rose significantly (P < or = 0.02) during the day in all groups. During Ang II infusion, EPO levels rose to significantly higher levels after 6 and 12 hours compared with placebo [9.9 +/- 3.5 vs. 7.2 +/- 3.1 mU/mL (3 h, P = NS); 16.9 +/- 4.5 vs. 8.8 +/- 3.7 mU/mL (6 h, P = 0.01); 17.0 +/- 8.6 vs. 11.1 +/- 4.7 mU/mL (12 h, P = 0.01)] and returned to baseline after 24 hours (7.9 +/- 3.8 vs. 10.6 +/- 8.6 mU/mL, P = NS). With AT1R blockade, blood pressure remained normal during Ang II infusion, and EPO levels were never significantly different from placebo [6.8 +/- 4.8, 10.5 +/- 5.6, 13.1 +/- 9.0, and 12.4 +/- 10.1 mU/mL at 3, 6, 12, and 24 h after infusion, respectively, P = NS].

CONCLUSIONS

Ang II increases EPO levels in humans. This increase requires the participation of AT1R.

Platelet CD62 expression and PDGFAB secretion in patients undergoing PTCA and treatment with abciximab

AIMS

To investigate a correlation of the platelet activation marker CD62 and secretion of the growth factor PDGF from platelets in coronary patients under therapy with the GPIIb/IIIa-inhibitor abciximab.

METHODS

Flow cytometric assessment of fibrinogen binding (GPIIb/IIIa-binding site) and CD62 expression, as well as PDGF release of human platelets (immunoassay) and platelet aggregation with 20 microM ADP and 2 microg ml(-1) collagen were evaluated in nine patients with stable coronary artery disease. Patients were undergoing elective balloon angioplasty and were treated with aspirin (100 mg day(-1)), heparin (ACT < 220 s) and abciximab (bolus and infusion over 12 h). Blood samples were obtained before initiation of abciximab therapy (under aspirin and heparin) (I), 3 h after angioplasty under abciximab (II) and 12 h after termination of abciximab infusion (III).

RESULTS

Compared with sample I before abciximab therapy, fibrinogen binding was reduced to 37% (+/- 34 s.d., P < 0.05) (II) and 55% (+/- 40 s.d., P < 0.05) (III). Reduced fibrinogen binding also led to a significant reduction of the aggregation response to ADP (down to 37% +/- 20) and collagen (down to 0%). Mean fluorescence intensity of CD62-expression was 78 units (+/- 20 s.d.) (I), 72 units (+/- 14 s.d.) (II) and 64 units (+/- 12 s.d., P < 0.05) (III). PDGF release from isolated, washed platelets was 99 (+/- 33 s.d.) ng/10(9) platelets at (I), 82 (+/- 31 s.d.) ng/10(9) platelets and 96 (+/- 30 s.d.) ng/10(9) platelets.

CONCLUSIONS

The results indicate that despite a strong reduction of GPIIb/IIIa-binding and platelet aggregation, CD62 as a marker of platelet secretion and the secretion product PDGF were only slightly reduced under abciximab treatment. No direct correlation between CD62 expression and PDGF release could be demonstrated.

No evidence for deletions of the NBS1 gene in lymphomas

Patients with Nijmegen breakage syndrome (NBS) have a high risk to develop malignant diseases, most frequently B-cell lymphomas. The NBS gene product, nibrin, is involved in DNA recombination repair, a function shared with known tumor suppressor genes like BRCA1 and BRCA2. This led us to investigate whether NBS acts as tumor suppressor gene in the development of non-Hodgkin lymphomas. Therefore, we performed fluorescence in situ hybridization analysis using a BAC clone containing the entire NBS1 region on eight B-cell and eight T-cell lymphomas, including one B-cell and two T-cell lymphomas with structural abnormalities of 8q. None of the tumors showed a deletion of the NBS1 gene, demonstrating that deletion of the NBS1 gene is not a major cause or a primary event in tumorigenesis of human B- and T-cell lymphomas.

In vitro dose response to different GPIIb/IIIa-antagonists: inter-laboratory comparison of various platelet function tests

AIMS

The aim of this study was to assess the inter- and intra-laboratory variation of the concentration-response to the GPIIb/IIIa-antagonists abciximab and eptifibatide on platelet aggregometry and to compare results with flow cytometric tests as well as the rapid platelet function analyser (RPFA).

METHODS

In five different laboratory sites, blood from three to five healthy donors was spiked with abciximab or eptifibatide, followed by the assessment of: (1) aggregometry (anticoagulant: sodium citrate 3.18% or hirudin 5 microg/ml); (2) flow cytometry (fibrinogen binding or PAC1-expression), or (3) RPFA. Dose-response curves were established on the basis of a sigmoidal Imax)-model [I=(Imax)*Cg)/(IC50g + Cg)].

RESULTS

For citrated blood, aggregation induced by 20 microM ADP was blocked up to 100% by both GPIIb/IIIa-antagonists, IC50 values varied between 0.11-0.22 microg/ml for eptifibatide and 1.25-2.3 microg/ml for abciximab. I(max) of the response to 5 microg/ml collagen ranged from 46% to 100%, and IC50 values varied between 0.28-0.34 microg/ml for eptifibatide and 2.3-3.8 microg/ml for abciximab. In hirudinized blood, IC50 values for eptifibatide were 1.5- to 3-fold higher than those obtained with citrated plasma. Inhibition of PAC1-expression by abciximab (IC50) 0.84 microg/ml) showed results similar those of the RPFA (approx. 1.0 microg/ml); larger differences between PAC1 and RPFA results were observed for eptifibatide. Based on aggregometry, eptifibatide concentrations for 80% inhibition varied from 0.27 to 0.55 microg/ml, and were considerably less when the RPFA was taken as basis (0.15 or 0.22 microg/ml). A similar pattern was observed for abciximab.

CONCLUSIONS

We found quite a low inter- and intra-laboratory variation in the in vitro pharmacodynamic characterization of GPIIb/IIIa-antagonists by aggregometry, making results of these tests obtained from different laboratories during clinical trials at least comparable. The RPFA exhibits a higher sensitivity to inhibitory GPIIb/IIIa-effects, in keeping with the "real" inhibition of the activated receptor (PAC1) as assessed with more elaborate flow cytometry.

Regulator of G protein signaling 4 suppresses basal and thyrotropin releasing-hormone (TRH)-stimulated signaling by two mouse TRH receptors, TRH-R(1) and TRH-R(2)

We cloned the mouse TRH receptor type 2 (mTRH-R2) gene, which is 92% identical with rat TRH-R2 and 50% identical with mTRH-R1 at the amino acid level, and identified an intron within the coding sequence that is not present in the TRH-R1 gene structure. Similar to its rat homolog, mTRH-R2 binds TRH with an affinity indistinguishable from mTRH-R1, signals via the phosphoinositide pathway like mTRH-R1, but exhibits a higher basal signaling activity than mTRH-R1. We found that regulator of G protein signaling 4 (RGS4), which differentially inhibits signaling by other receptors that couple to Gq, inhibits TRH-stimulated signaling via mTRH-R1 and mTRH-R2 to similar extents. In contrast, other RGS proteins including RGS7, RGS9, and GAIP had no effect on signaling by mTRH-R1 or mTRH-R2 demonstrating the specificity of RGS4 action. Interestingly, RGS4 markedly inhibited basal signaling by mTRH-R2. Inhibition of basal signaling of mTRH-R2 by RGS4 suggests that modulation of agonist-independent signaling may be an important mechanism of regulation of G protein-coupled receptor activity under normal physiologic circumstances.

The relation between initial symptoms and signs and the prognosis of whiplash

Whiplash, a common injury following motor vehicle crashes, is associated with high costs and a prognosis that is variable and difficult to predict. We studied the profile of recovery from whiplash and assessed whether presenting signs and symptoms directly after the crash were predictive of whiplash prognosis. We formed a population-based incident cohort of all 2627 individuals who sustained a whiplash injury resulting from a motor vehicle crash in the province of Québec, Canada, in 1987, and followed these patients for up to 7 years. The data on signs and symptoms were obtained from the medical charts kept by the universal automobile insurance plan (Société de l'assurance automobile du Québec), which covers all 7 million residents of the province, while data on the outcome--the recovery time from whiplash--was obtained from their databases. The median recovery time was 32 days, and 12% of subjects had still not recovered after 6 months. The signs and symptoms that were found to be independently associated with a slower recovery from whiplash, besides female gender and older age, are neck pain on palpation, muscle pain, pain or numbness radiating from the neck to arms, hands or shoulders, and headache. Together, these factors in older females (age 60) predicted a median recovery time of 262 days, compared with 17 days for younger males (age 20) who do not have this profile. In contrast, using a classification of injury severity previously proposed by the Québec Whiplash Associated Disorders Task Force, the median recovery time varied from 17 to only 123 days. We conclude that whiplash patients presenting with several specific musculoskeletal and neurological signs and symptoms will have a longer recovery period. These patients can easily be identified and closely monitored and targeted for the evaluation of early intervention programmes aimed at managing whiplash patients with a poor prognosis.