Magnetocaloric effect and improved relative cooling power in (La(0.7)Sr(0.3)MnO(3)/SrRuO(3)) superlattices

Magnetic properties of a series of (La(0.7)Sr(0.3)MnO(3)/SrRuO(3)) superlattices, where the SrRuO(3) layer thickness is varying, are examined. A room-temperature magnetocaloric effect is obtained owing to the finite size effect which reduces the T(C) of La(0.7)Sr(0.3)MnO(3) layers. While the working temperature ranges are enlarged, - ΔS(M)(max) values remain similar to the values in polycrystalline La(0.7)Sr(0.3)MnO(3). Consequently, the relative cooling powers are significantly improved, the microscopic mechanism of which is related to the effect of the interfaces at La(0.7)Sr(0.3)MnO(3)/SrRuO(3) and higher nanostructural disorder. This study indicates that artificial oxide superlattices/multilayers might provide an alternative pathway in searching for efficient room-temperature magnetic refrigerator for (nano) micro-scale systems.

Expression, purification, and characterization of a His6-tagged glycerokinase from Pichia farinosa for enzymatic cycling assays in mammalian cells

The GUT1 gene of the halotolerant yeast Pichia farinosa, encoding glycerokinase (EC 2.7.1.30), was expressed in Pichia pastoris. A purification factor of approximately 61-fold was achieved by a combination of nickel affinity and anion exchange chromatography. The specific activity of the final preparation was 201.6 units per mg protein with a yield of about 21%. A nearly homogeneous enzyme preparation was confirmed by SDS-polyacrylamide gels and mass spectrometry analysis. Glycerol stabilized the purified enzyme for long-term storage at -80°C. The pH and temperature optima were in the range of 6.5-7.0 and 45-50°C, respectively. ATP was the most effective phosphoryl group donor tested. Additionally, the enzyme phosphorylated glycerol also with ITP, UTP, GTP and CTP. The K(m) values of the enzyme for ATP and ITP were 0.428 and 0.845 mM, respectively. The kinetic properties of the enzyme with respect to UTP, GTP, and CTP suggested that glycerokinase exhibited negative cooperativity as double reciprocal plots showed a biphasic response to increasing nucleoside triphosphate concentrations. The application as a coupling enzyme in the determination of pyruvate kinase activity in cell extracts of Madin-Darby canine kidney cells showed good reproducibility when compared with a commercially available preparation of bacterial glycerokinase.

Evaluation of the effect of TRU-016, an anti-CD37 directed SMIP in combination with other therapeutic drugs in models of non-Hodgkin's lymphoma

8571

Background: TRU-016, a single chain anti-CD37 Fc fusion molecule has been shown to display pro-apoptotic and Fc-dependent cellular cytotoxicity activities against primary CLL cells and NHL cell lines. The pro-apoptotic signal generated by TRU-016 binding to CD37 on CLL cells has been shown to be caspase-independent and distinct from the signal generated by many other therapeutics including rituximab. We have tested drug combinations using the mantle cell lymphoma line Rec-1 and diffuse large B-cell lymphoma line SU-DHL-6 in vitro and extended these results to in vivo settings using the follicular lymphoma cell line DOHH2 treated with the combination of TRU-016 and bendamustine. Methods: To determine TRU-016 interactions with the established therapeutics rituximab, doxorubicin, rapamycin, and bendamustine, drugs were tested alone or in combination with TRU-016 and the anti-proliferative effects on cell lines measured after 96 hours. Combination index analysis was performed for drug combinations over the 20–90% effect levels using the Calcusyn software package. To determine if in vitro synergy could be recapitulated in vivo, SCID mice were implanted with DOHH2 cells and therapeutic treatment was initiated when tumor volumes reached 200 mm3. Treatments consisted of TRU-016, bendamustine, or the combination of TRU-016 and bendamustine. Results: Combination index analyses determined that TRU-016 is synergistic with rituximab, bendamustine, or rapamycin and additive with doxorubicin in NHL models. In vivo results show that treatment with the combination of TRU-016 and bendamustine resulted in increased efficacy compared to the efficacy attained with the individual drugs. This demonstrates that the in vitro synergy results were extendable to a more complex in vivo disease model. Conclusions: TRU-016 in combination with rituximab, rapamycin, or bendamustine increases cell killing of NHL cells. Furthermore, the combination of TRU-016 and bendamustine displayed greater in vivo anti-tumor activity than either agent alone against a follicular lymphoma tumor model.

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Long-term results after fluoroscopy-guided closure of patent foramen ovale for secondary prevention of paradoxical embolism

OBJECTIVES

To carry out long-term follow-up after percutaneous closure of patent foramen ovale (PFO) in patients with cryptogenic stroke.

DESIGN

Prospective cohort study.

SETTING

Single tertiary care centre.

PARTICIPANTS

525 consecutive patients (mean (SD) age 51 (12) years; 56% male).

INTERVENTIONS

Percutaneous PFO closure without intraprocedural echocardiography.

MAIN OUTCOME MEASURES

Freedom from recurrent embolic events.

RESULTS

A mean (SD) of 1.7 (1.0) clinically apparent embolic events occurred for each patient, and 186 patients (35%) had >1 event. An atrial septal aneurysm was associated with the PFO in 161 patients (31%). All patients were followed up prospectively for up to 11 years. The implantation procedure failed in two patients (0.4%). There were 13 procedural complications (2.5%) without any long-term sequelae. Contrast transoesophageal echocardiography at 6 months showed complete closure in 86% of patients, and a minimal, moderate or large residual shunt in 9%, 3% and 2%, respectively. Patients with small occluders (<30 mm; n = 429) had fewer residual shunts (small 11% vs large 27%; p<0.001). During a mean (SD) follow-up of 2.9 (2.2) years (median 2.3 years; total 1534 patient-years), six ischaemic strokes, nine transient ischaemic attacks (TIAs) and two peripheral emboli occurred. Freedom from recurrent stroke, TIA, or peripheral embolism was 98% at 1 year, 97% at 2 years and 96% at 5 and 10 years, respectively. A residual shunt (hazard ratio = 3.4; 95% CI 1.3 to 9.2) was a risk factor for recurrence.

CONCLUSIONS

This study attests to the long-term safety and efficacy of percutaneous PFO closure guided by fluoroscopy only for secondary prevention of paradoxical embolism in a large cohort of consecutive patients.

Depletion of Normal and Malignant B cells with a CD37-specific SMIP molecule

3063

Background: CD37 is a member of the tetraspanin family expressed at high levels by normal mature B cells and by most B cell malignancies. Previously, an antibody to CD37 has been labeled with 131I and tested in clinical trials for therapy of NHL. Treatment with 131I-MB-1, resulted in durable tumor remissions in patients lasting from 4 to 11 months (Press OW, Eary JF, Badger CC, et al. Treatment of refractory non-Hodgkin’s lymphoma with radiolabeled MB-1 (anti-CD37) antibody. J Clin Oncol. 1989;7:1027–1038). Here we assess the functional properties and therapeutic potential of a small modular immunopharmaceutical (SMIP) targeting CD37. Methods: Growth arrest and apoptosis of B lymphoma cell lines was assessed. ADCC activity was evaluated using BJAB targets and human peripheral blood mononuclear cells (PBMC) effectors. Drug-drug interactions were assessed by the Combination Index method. In vivo studies were performed utilizing established human B cell tumor xenografts in nude mice. Results: A CD37-directed SMIP drug candidate mediated growth arrest, apoptosis and ADCC, but not CDC, towards B lymphoma cell lines. The protein showed significant anti-tumor activity in a mouse xenograft model, and selectively depleted normal human B cells in short term cultures of PBMC. When combined with rituximab, the molecule increased apoptosis, C1q binding, and C’ dependent target cell death in vitro, and increased anti-tumor activity in vivo in a xenograft model. Conclusions: In vitro and in vivo characterization of the CD37-targeted SMIP drug suggest a potent capacity to eliminate target cells through combined effects of direct target cell signaling and effector cell recruitment. CD37-mediated growth was synergistic with standard chemotherapies in vitro and showed additive in vivo activity with CD20-targeted therapy. On the basis of these data CD37-directed SMIP therapy is being developed for clinical evaluation against B cell malignancies.

No significant financial relationships to disclose.

Fluorescence quencher improves scansystemtm for rapid bacterial detection

BACKGROUND AND OBJECTIVES

The optimized scansystem could detect contaminated platelet products within 24 h. However, the system's sensitivity was reduced by a high fluorescence background even in sterile samples, which led to the necessity of a well-trained staff for confirmation of microscope results.

MATERIALS AND METHODS

A new protocol of the optimized scansystem with the addition of a fluorescence quencher was evaluated. Pool platelet concentrates contaminated with five transfusion-relevant bacterial strains were tested in a blind study.

RESULTS

In conjunction with new analysis software, the new quenching dye was able to reduce significantly unspecific background fluorescence. Sensitivity was best for Bacillus cereus and Escherichia coli (3 CFU/ml).

DISCUSSION

The application of a fluorescence quencher enables automated discrimination of positive and negative test results in 60% of all analysed samples.