Tariquidar-induced P-glycoprotein inhibition at the rat blood-brain barrier studied with (R)-11C-verapamil and PET.

The multidrug efflux transporter P-glycoprotein (P-gp) is expressed in high concentrations at the blood-brain barrier (BBB) and is believed to be implicated in resistance to central nervous system drugs. We used small-animal PET and (R)-11C-verapamil together with tariquidar, a new-generation P-gp modulator, to study the functional activity of P-gp at the BBB of rats. To enable a comparison with human PET data, we performed kinetic modeling to estimate the rate constants of radiotracer transport across the rat BBB. METHODS: A group of 7 Wistar Unilever rats underwent paired (R)-11C-verapamil PET scans at an interval of 3 h: 1 baseline scan and 1 scan after intravenous injection of tariquidar (15 mg/kg, n = 5) or vehicle (n = 2). RESULTS: After tariquidar administration, the distribution volume (DV) of (R)-11C-verapamil was 12-fold higher than baseline (3.68 +/- 0.81 vs. 0.30 +/- 0.08; P = 0.0007, paired t test), whereas the DVs were essentially the same when only vehicle was administered. The increase in DV could be attributed mainly to an increased influx rate constant (K1) of (R)-11C-verapamil into the brain, which was about 8-fold higher after tariquidar. A dose-response assessment with tariquidar provided an estimated half-maximum effect dose of 8.4 +/- 9.5 mg/kg. CONCLUSION: Our data demonstrate that (R)-11C-verapamil PET combined with tariquidar administration is a promising approach to measure P-gp function at the BBB.     

Perforated colorectal neoplasms: correlation of clinical, contrast enema, and CT examinations

Results of clinical, contrast enema (CE), and computed tomographic (CT) examinations in 39 patients with perforated colorectal neoplasms were retrospectively reviewed. Twenty patients were toxemic at initial presentation, but in only four patients was the diagnosis of perforated colorectal neoplasm initially suspected clinically. CE study was performed in 22 patients and enabled the diagnosis of perforated neoplasm in 11 cases, neoplasm alone in eight, and neither neoplasm nor perforation in three. CT was performed in 38 patients and enabled the diagnosis of perforated neoplasm in 36; pericolic phlegmon but no mass lesion was evident in two. In 16 patients, CT also demonstrated metastatic disease. Because of its reliability in establishing the diagnosis and staging the extent of the inflammatory and neoplastic disease, CT is indicated in cases of suspected or proved perforated colorectal neoplasm and in cases in which CE study findings are indeterminate or suggestive of perforated neoplasm.     

Preliminary characterization of Borrelia burgdorferi CSF isolates

Summary Borrelia burgdorferi was cultivated from three cerebrospinal fluid (CSF) samples of children (aged three and a half, four and a half and eight years) who were admitted to the hospital because of acute facial palsy, aseptic meningitis, and aseptic meningitis plus facial palsy. CSF was taken on day one in two cases and on day two in the remaining case after onset of symptoms. All three strains showed a very similar SDS-PAGE pattern, without an OspB and 20kD band. However, of nine monoclonal antibodies (Moab) raised againstB. burgdorferi B31, the Moab H5332 recognized two strains, one of them very weakly, and the flagella specific Moabs H9724, H605, and H6TS (less intensively) recognized all strains. This preliminary characterization reveals heterogeneity among CSFBorrelia isolates of cases from a very close geographic area.

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Vorläufige Charakterisierung von Borrelia burgdorferi-Liquor-Isolaten

Zusammenfassung Borrelia burgdorferi wurde aus drei Liquorproben von Kindern (Alter: dreieinhalb, viereinhalb und acht Jahre) angezüchtet, welche aufgrund akuter Fazialisparese, aseptischer Meningitis und aseptischer Meningitis mit Fazialisparese ins Krankenhaus eingeliefert worden waren. Liquor wurde in zwei Fällen am ersten Tag, in einem am zweiten Tag nach Auftreten der Symptome gewonnen. Die drei Borrelien-Isolate waren in ihrem SDS-PAGE-Muster sehr ähnlich. Sie unterschieden sich jedoch in ihrer Reaktion mit neun monoklonalen Antikörpern (MoAb), die gegen den TypstammB. burgdorferi B31 entwickelt worden waren. MoAb H5332 erkannte zwei Stämme, einen davon in einer sehr schwachen Reaktion; die Flagella-spezifischen MoAbs H9724, H605 und H6TS, dieser weniger intensiv, erkannten alle Stämme. Diese vorläufige Charakterisierung zeigt Heterogenität unterB. burgdorferi-Liquor-Isolaten von Patienten aus der gleichen geografischen Region.

     

Frequent ongoing T-cell receptor rearrangements in childhood B- precursor acute lymphoblastic leukemia: implications for monitoring minimal residual disease

Crosslineage T-cell receptor delta (TCR delta) rearrangements are widely used as tumor markers for the follow up of minimal residual disease in childhood B-precursor acute lymphoblastic leukemia (ALL) by polymerase chain reaction (PCR). The major drawback of this approach is the risk of false-negative results due to clonal evolution. We investigated the stability of V delta 2D delta 3 rearrangements in a group of 56 childhood B-precursor ALL patients by PCR and Southern blot analysis. At the PCR level, V delta 2D delta 3-to-J alpha rearranged subclones (one pathway for secondary TCR delta recombination) were demonstrated in 85.2% of V delta 2D delta 3-positive patients tested, which showed that small subclones are present in the large majority of patients despite apparently monoclonal TCR delta Southern blot patterns. Sequence analysis of V delta 2D delta 3J alpha rearrangements showed a biased J alpha gene usage, with HAPO5 and J alpha F in 26 of 32 and 6 of 32 clones, respectively. Comparison of V delta 2D delta 3 rearrangement status between diagnosis and first relapse showed differences in seven of eight patients studied. In contrast, from first relapse onward, no clonal changes were observed in six patients studied. To investigate the occurrence of crosslineage TCR delta rearrangements in normal B and T cells, fluorescence-activated cell sorter-sorted peripheral blood CD19+/CD3- and CD19-/CD3+ cell populations from three healthy donors were analyzed. V delta 2D delta 3 rearrangements were detected at low frequencies in both B and T cells, which suggests that V delta 2-to-D delta 3 joining also occurs during normal B-cell differentiation. A model for crosslineage TCR delta rearrangements in B-precursor ALL is deduced that explains the observed clonal changes between diagnosis and relapse and is compatible with multistep leukemogenesis of B-precursor ALL.     

Borrelia burgdorferi infections — A survey after a decade

Supported by Biochemie Wien and Hoffmann-La Roche.