Monoclonal antibodies to guinea pig interferon-gamma: tools for cytokine detection and neutralization

We have generated polyclonal antisera and monoclonal antibodies against recombinant guinea pig IFN-gamma. These antibodies were used to inhibit the function of IFN-gamma in vitro and to establish a capture ELISA system for the detection and quantitation of this cytokine. Although recombinant protein expressed in E. coli was available in abundance, it was only of limited value to develop a capture ELISA which detects the native cytokine, since only a limited number of monoclonal antibodies reacted both with the recombinant and the native protein. Positive test results in an initial ELISA setup with recombinant IFN-gamma were not predictive for the detection of IFN-gamma from activated T-lymphocytes in the same assay. After evaluating several different combinations of rabbit antisera and monoclonal antibodies, an assay system was established which uses two mouse monoclonal antibodies as capture and detecting reagents. Three of the monoclonal antibodies and the rabbit antisera were able to block the function of guinea pig IFN-gamma when assayed in a luciferase reporter assay.

Effect of the green tea polyphenol epigallocatechin gallate (EGCG) on growth and IL-6 signalling pathways in malignant plasma cells

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Background: Epigallocatechin gallate (EGCG) is the predominant polyphenolic constituent of green tea leaves that possesses antitumor, antiinflammatory, and antioxidant activity. EGCG exerts its effects through potentially multiple mechanisms including inhibition of growth factor receptor signalling. The compound is currently under investigation in a phase I/II clinical trial for treatment of patients with early stage chronic lymphocytic leukemia at Mayo Clinic. The goal of our study was to examine the in vitro effects of EGCG in multiple myeloma (MM). Methods: A panel of human myeloma cell lines (n=6) including the IL-6 dependent INA-6 cell line was used to evaluate the sensitivity to EGCG. Cells were cultured for three days in the absence or presence of EGCG at concentrations between 6.25 μM and 100 μM. Cell viability was determined in a colorimetric tetrazolium (MTS) based assay and by trypanblue exclusion. For signalling experiments, INA-6 cells were IL-6 and serum starved and then treated with EGCG for two hours before IL-6 was added. Whole cell lysates were prepared and subjected to SDS-PAGE and Western blot analysis. Results: EGCG inhibited the in vitro growth of human myeloma cell lines by inducing cell death in a time and dose-dependent manner. IC50 concentrations were between 12,5 μM and 50 μM. IL-6 mediated growth of INA-6 cells was inhibited at similar doses. The addition of excess amounts of IL-6 could not protect from EGCG induced cytotoxicity. Pretreatment of INA-6 cells with EGCG resulted in a dose-dependent inhibition of IL-6 induced STAT3 tyrosine phosphorylation. In these cells, stimulation with IL-6 leads to upregulation of Mcl-1 expression. In contrast, phosphorylation of p44/p42 MAPK, which is constitutively activated in INA-6 cells, was not affected. Conclusion: EGCG has growth inhibitory activity on myeloma cells. Specific inhibition of signalling pathways that regulate expression of anti-apoptotic proteins could be one mechanism how EGCG exerts its activity. Our work provides the rationale for further studies to evaluate the effect of EGCG not only in B-CLL, but also in plasma cell tumors.

No significant financial relationships to disclose.

Therapeutic drug monitoring of quetiapine in adolescents with psychotic disorders

INTRODUCTION

There are developmental and age-dependent differences in the pharmacokinetics and the pharmacodynamics of drugs in children and adolescents. Therefore, there is a need to carry out standardised studies to find out therapeutic ranges of plasma/serum concentrations in psychopharmacotherapy of children and adolescents. The aim of this prospective study was to examine the relationship between quetiapine serum concentration, treatment response, and side effects in a clinical setting to elucidate the age-specific therapeutic range of quetiapine in adolescents.

METHODS

Over a period of two years, therapeutic drug monitoring (TDM) was routinely performed in 21 adolescents (mean age was 15.9+/-1.5 years, 57% male) with psychotic disorders according to the guidelines of the AGNP TDM expert group. The psychopathology was assessed by using the Clinical Global Impression Scale (CGI) and the Brief Psychiatric Rating Scale (BPRS). Side effects were assessed by using the Dose Record and Treatment Emergent Symptom Scale (DOTES). Trough quetiapine concentrations were determined under steady state conditions after multiple-dose regimes (median 600 mg/day; range 100-800 mg/day).

RESULTS

There was a marked variability of the serum concentrations, ranging from 19-877 ng/ml. 40.8% of the determined values were below and 24.5% above the therapeutic range (70-170 ng/ml) recommended for adults. None of the patients had severe side effects. We found a weak correlation between dose and serum concentration of quetiapine and no relationship between serum concentration and treatment response.

DISCUSSION

There are several limitations of this study, and our results should therefore be interpreted with caution. Notwithstanding, differences in the ontogenesis of pharmacokinetics and pharmacodynamics may be the reason for the difference in the relationship between blood concentrations and therapeutic response to psychopharmaca in children, adolescents and adults. Further studies using larger samples, baseline assessment of psychopathology, definition of the treatment interval and investigation of clinically relevant interactions with various co-medications are warranted to improve the limitations of this pilot study.

Therapeutic drug monitoring of tricyclic antidepressants in everyday clinical practice

Data about therapeutic drug monitoring (TDM) of psychotropic medications are often obtained from samples of highly selected individuals, who may not be representative for the average psychiatric patient. These data therefore may have limitations with regard to their transferability to everyday clinical practice. Therefore studies under naturalistic conditions are important to clarify the full clinical relevance of TDM. We retrospectively evaluated all TDM-analyses of the tricyclic antidepressants (TCA) amitriptyline and clomipramine during a 12-month period in an unselected sample of patients in a standard clinical setting. We especially examined the relationship between serum levels on one hand and clinical response and adverse effects on the other hand. In patients with amitriptyline, responders showed a significantly higher serum level than non-responders, whereas in patients with clomipramine a serum level within the recommended therapeutic range was associated with clinical response. We also found significantly higher serum concentrations in patients with adverse effects compared to patients without adverse effects in the clomipramine group. No such relationship could be shown in patients treated with amitriptyline. Our results suggest that therapeutic ranges in naturalistic settings in some ways differ from those obtained in controlled clinical settings and that TDM studies in everyday clinical practice are necessary and beneficial.

Neuordnung des Verfahrens und der Aufgaben der zust�ndigen Ethik-Kommissionen

Since 12(th) of August 2004 the EU Directive 2001/20/EG has been implemented into the national law. The 12th AMG amendment of 30 July 2004 and the good clinical practice decree on the conduct of clinical trials on drugs for human use of 9 August 2004 have been authorized and must be considered for new clinical trials with investigational medical products (drugs). The scope of the changes are to increase the quality of clinical trials and to continue the process of harmonization within the European Community. Based on the new law the sponsor has to apply for approval by the competent authority and for a favourable opinion by the responsible ethics committee. Both procedures are independent; a favourable opinion of the responsible ethics committee is a necessary condition before starting the trial. Thus, the role of the ethics committees has been changed; the committees are considered as an institution comparable to an authority to protect the rights and safety of human subjects involved in clinical trials. The permanent working group of the medical ethics committees in Germany has established a procedure to meet these requirements, particularly in the case of multicentre clinical trials, where only a single opinion shall be given for each member state. This article describes this procedure (application, process of ethical consideration among the leading and local ethics committees in multicentre trials, responsibilities during the trial).

Brain aging phenomena in migrating sockeye salmon Oncorhynchus nerka nerka

Aging, a process occurring in all vertebrates, is closely related to a loss in physical and functional abilities. There is widespread interest in clarifying the relevance of environmental, metabolic, and genetic factors for vertebrate aging. In the Pacific salmon a dramatic example of aging is known. Looking for changes in the salmon brain, perhaps even in the role of initiating the aging processes, we investigated several biochemical parameters that should reflect brain functional activity and stress response such as the neurotransmitters dopamine, and serotonin, and two of their respective metabolites 3,4-dihydroxyphenylacetic acid, and 5-hydroxyindole acetic acid, as well as glutathione, glutathione disulfide, and the extent of terminal deoxynucleotidyltransferase-mediated dUTP nick end-labelling. The aging of migrating sockeye salmon (Oncorhynchus nerka nerka) is accompanied by gradual increase in dopamine and serotonin turnover and a gradual decrease of brain total protein and glutathione levels. There appears to be an increased need for detoxification of reactive biological intermediates since activities of superoxide dismutase and catalase increase with age. However, our data do not support a major increase in apoptotic cell death during late aging but rather implicate an age related downward regulation of protein and glutathione synthesis and proteolysis increasing the need for autophagocytosis or heterophagocytosis in the course of cell death.

Normalwerte der Herzdurchmesser in der Cine-MRT

PURPOSE

To measure the normal diameters of cardiac cavities in standard cardiac views using cine MRI.

MATERIALS AND METHODS

Fifty-six volunteers were examined (27 male, 29 female) on a 1.5 T MR unit with ECG-triggered single shot free precision (SSFP) cine MR sequences and parallel image acquisition. Standardized echocardiographic planes were used to depict the heart of all volunteers (short axis, 4-chamber view, left and right 2-chamber views). The different diameters of the cardiac cavities were measured using a fixed protocol.

RESULTS

For the estimation of ventricular dilatation, the important female/male cross diameters of the left ventricle are 45.2 +/- 3.4/51.6 +/- 4.6 mm diastolic and 30.5 +/- 3.5/33.8 +/- 3.6 mm systolic, and of the right ventricle 30.7 +/- 3.8/37.1 +/- 5.9 mm diastolic and 22.3 +/- 3.8/28.1 +/- 4.4 mm systolic. For the determination of a left ventricular hypertrophy, relevant septal wall thickness measured in the short axis of the left ventricle of female/male volunteers are 8.0 +/- 1.0/9.9 +/- 1.2 mm diastolic and 10.9 +/- 1.4/13.6 +/- 1.9 mm systolic. The measured normal values of male volunteers were generally higher than those of female volunteers. The thickness of the ventricular septum correlated well when measured in the short axis and 4-chamber view. When measured in the 4-chamber view, the longitudinal diameter of the ventricles had a higher value in diastole and a lower value in systole, compared to the 2-chamber views of the right and left cardiac cavities. The atrial longitudinal diameters were higher in the 4-chamber view compared to the 2-chamber views, without any difference in systole or diastole.

CONCLUSION

Diameters of cardiac cavities are easily and quickly measured. Using the tables with the normal values published here, it is simple to estimate an abnormal size of the heart.

["Emerging infectious diseases". Dengue-fever, West-Nile-fever, SARS, avian influenza, HIV]

Some emerging infectious diseases have recently become endemic in Germany. Others remain confined to specific regions in the world. Physicians notice them only when travelers after infection in endemic areas present themselves with symptoms. Several of these emerging infections will be explained. HIV is an example for an imported pathogen which has become endemic in Germany. SARS and avian influenza are zoonoses with the potential to spread from person to person. Avian influenza in humans provides a possibility for the reassortment of a potential new pandemic strain. Outbreaks of dengue fever in endemic areas are reflected in increased infections in travelers returning from these areas. Currently, West-Nile-virus infections are only imported into Germany. The timely implementation of diagnostic, therapeutic and infection control measures requires physicians to include these diseases in their differential diagnosis. To achieve this goal, good cooperation between physicians, laboratories and the public health service is essential.

Titer determination of Ad5 in blood: a cautionary note

Recombinant adenoviruses are presently the most efficient in vivo gene transfer system available. Targeting single organs or large tumors by adenoviral vectors requires an intravascular route of application. During the first pass of viral particles through the vascular bed of the target tissue, virus uptake is not quantitative and indefinite amounts of particles leak into circulation. To determine the amount of leaking particles and to calculate organ-specific uptake (in-/outflow ratio), it is necessary to titrate virus particles directly in blood. In preclinical and clinical trials titration is currently mostly done with blood plasma instead of full blood. However, this technique provides valid results only as long as there is no affinity between adenovirus particles and erythrocytes. In this study we demonstrate that Ad5 particles, as mostly employed for gene therapy, have a strong affinity to human erythrocytes. At 60 min after coincubation of human erythrocytes and Ad5 particles, more than 98% of the particles are attached to the surface of erythrocytes. Therefore, ignoring the amount of red cell bound particles by performing titration in plasma leads to severe miscalculation of organ-specific transfer rates or virus circulation half-life. The biological impact of an increased affinity between virus particles and erythrocytes will be discussed.

Dynamic correlation between tissue PO2 and near infrared spectroscopy

Multimodal O2 monitoring including tissue pO2 measurements and near infrared spectroscopy (NIRS) are techniques increasingly employed for monitoring patients on neurosurgical intensive care units. NIRS measures a mixed venous arterial oxygen saturation, whereas tissue pO2 evaluates the oxygen pressure in the white matter. In contrast to the tissue pO2 measurements, the NIRS at the moment has not been completely established in clinical practice. We wanted to evaluate whether both techniques are monitoring different dynamic changes. Thirteen patients were included (SAH n = 3, TBI n = 10), 12 patients were male and 1 was female. Mean age was 34 years with a range from 16-76 years. Tissue pO2 probes (Licox, GMS, Germany) were implanted in the frontal lobe showing most pathological changes on the initial CT scan. A near infrared spectroscopy sensor (Invos, Somanetics, USA) was placed simultaneously at the patient's forehead. Due to the drift of the tissue pO2 probe, only data sets were taken into further account in which a tissue pO2 value above 15 mmHg was measured. 66 data sets were analyzed by calculating the spectral coherence with multi taper methods. The coherence of two independent white noise signals were defined as an observation by chance. The significance level for correlated frequencies was 90%. In the spectral long time regime (frequency > or = 0.02), more than 80% of the data sets showed a higher percentage of correlated frequencies as compared to the observation by chance. The assumption that tissue pO2 and near infrared spectroscopy probes are measuring different dynamic changes in neurosurgical intensive care patients could not be supported by our data.

Gp130 and ras mediated signaling in human plasma cell line INA-6: a cytokine-regulated tumor model for plasmacytoma

INTRODUCTION

Cytokines of the gp130-family, particularly interleukin(IL)-6, play a crucial role in the propagation of malignant plasma cells.

MATERIALS AND METHODS

The role of IL-6 and other gp130-cytokines was studied in the human plasma cell line INA-6 in vitro and in INA-6 xenografts. The proliferative response to gp130-cytokines was evaluated and activated components of gp130-signaling pathways were identified by Western blotting and DNA binding studies. Specifically, expression of IL-6 and receptors for IL-6 and leukemia inhibitory factor were analysed by RT-PCR and ELISA.

RESULTS

The plasma cell line INA-6 was cultured for several years remaining strictly dependent on exogenous IL-6. Other gp130-cytokines had no significant effect on INA-6 cell proliferation in vitro. Due to an activating mutation in the N-ras gene, mitogen-activated protein kinases (MAPK) were constitutively phosphorylated. In contrast, signal transducer and activator of transcription(STAT)-3 activation was dependent on stimulation with IL-6. Blocking of either one of these pathways resulted in a significant decrease of INA-6 cell proliferation. Remarkably, INA-6 xenografts did not require exogeneous IL-6 for proliferation in vivo. Instead, an autocrine IL-6 loop and, in certain tumor sublines, responsiveness to additional gp130-cytokines was induced during in vivo growth.

CONCLUSION

Activation of the gp130 signal transducer is mandatory for INA-6 cell growth in vitro and in vivo. Both the MAPK and the Jak/STAT pathway are operative in malignant plasma cells and either one is essential for plasma cell growth. The INA-6 cell line provides a preclinical model to study growth regulation of human plasmacytoma cells and to evaluate novel therapeutic strategies.