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Background Epstein-Barr virus (EBV) is a ubiquitous pathogen that chronically infects B lymphocytes and is implicated in the pathogenesis of lymphoproliferative diseases. Latent membrane protein 1 (LMP1), the major oncoprotein of the virus, has been shown to inhibit apoptosis and trigger survivin expression in malignant cell lines. LMP1 expression has been detected in patients with chronic lymphocytic leukemia, but its properties have not been studied in patients with low-grade B-cell lymphomas. Recent data show that LMP1 can simultaneously induce and inhibit apoptosis in B cells. We detected LMP1 messenger RNA (mRNA) in patients with leukemic low-grade B-cell lymphoma and correlated the expression of the antiapoptotic molecule survivin to that of LMP1 in this group of patients. Patients and Methods Peripheral whole blood from 64 patients with low-grade B-cell lymphoma was tested by quantitative reverse transcriptase–polymerase chain reaction (PCR) for the presence of the BXLF-1 gene of EBV, and positive samples were tested by conventional PCR for LMP1 expression. Accordingly, survivin mRNA levels were measured by quantitative reverse transcriptase PCR in all samples and compared between LMP1-positive (LMP1 + ) and LMP1 − patients. Results The BXLF-1 gene was detected in 27 of 64 patients (42%). LMP1 was expressed in 22 of 27 (81%) EBV + patients. Survivin expression was found to be 6.36 times higher in LMP1 − patients than in LMP1 + patients ( P = .008). Conclusion Our results imply that in patients with non–EBV-related leukemic low-grade B-cell lymphoma, LMP1 expression is possibly correlated to apoptosis, as indicated by the lower survivin mRNA levels in LMP1 + patients.

Bcl-6 is essential for germinal centre development and normal antibody responses, and has major roles in controlling B-cell proliferation and differentiation. Bcl-6 expression is tightly controlled, but neither the nature of all the regulatory signals nor their interactions are known. Bcl-6 expression is induced in Bcr-Abl expressing lymphoid cell lines by the tyrosine kinase inhibitor, imatinib. We show that p38 MAPK mediates induction of Bcl-6 following inhibition of Bcr-Abl by imatinib. Next we analyze p38 function in a germinal centre B-cell line, Ramos. p38 is phosphorylated under basal conditions, and studies with p38 inhibitors show that it induces Bcl-6 expression. Membrane bound CD40 ligand activates p38 but also other MAPK pathways that strongly repress Bcl-6 and the overall effect is reduction in Bcl-6 expression. Surprisingly soluble CD40 ligand induces Bcl-6 by activating p38 without activating the repressive pathways. Hence different types of CD40 signalling are associated with varying effects on Bcl-6 expression. Transcription reporter assays demonstrate p38 responsive sequences at about 4.5 kb from the transcription start site. Immunocytochemistry of tonsil sections show phosphorylated p38 in a minor population of germinal centre B-cells. We demonstrate for the first time that p38 induces Bcl-6 transcription, but increased protein expression occurs only when the strong pathways repressing Bcl-6 are not activated.

The aim of this work is to develop biopharmaceutics classification systems for new molecular entities (BCS-NMEs) and marketed drugs (BCS-MD). The kinetics of gastrointestinal (GI) wall permeation and dissolution were re-considered theoretically. The relationships between the solubility/dose ratio and the fractions of dose dissolved and absorbed, were also examined. Mean time calculations for drug dissolution (MDT) and permeation (MPT) of the GI wall were analyzed in respect to the mean intestinal transit time (MITT) to identify a cutoff point for drug dissolution and GI wall permeation. Dissolution experiments for marketed drugs were carried out. NMEs were classified into four classes of BCS-NMEs, based on solubility/dose ratio and apparent permeability estimates. A physiologically based cutoff time point for dissolution and permeation was used to differentiate rapidly from slowly dissolving-permeating marketed drugs, which were classified into four classes of BCS-MD using their dissolution index (DI = MITT/MDT) and permeation index (PI = MITT/MPT) values as follows: I (DI ≥ 3, PI ≥ 3), II (DI < 3, PI ≥ 3), III (DI ≥ 3, PI < 3) and IV (DI < 3, PI < 3). In conclusion, two classification systems were developed, one for NMEs based on solubility/dose ratio and permeability estimates and one for marketed drugs based on MDT and MPT estimates.

A reaction-limited model for drug dissolution is developed assuming that the reaction at the solid-liquid interface is controlling the rate of dissolution. The dissolution process is considered as a bidirectional chemical reaction of the undissolved drug species with the free solvent molecules, yielding the dissolved species of drug complex with solvent. This reaction was considered in either sink conditions, where it corresponds to the unidirectional case and the entire amount of the drug is dissolved, or reaching chemical equilibrium, which corresponds to saturation of the solution. The model equation was fitted successfully to dissolution data sets of naproxen and nitrofurantoin formulations measured in the paddle and basket apparatuses, respectively, under various experimental conditions. For comparative purposes these data were also analyzed using three functions based on the diffusion layer model. All functions failed to reveal the governing role of saturation solubility in the dissolution process associated with the diffusion layer model when the conditions for the valid estimation of saturation solubility, established theoretically in this study, were met by the experimental set up employed. Overall, the model developed provides an interesting alternative to the classic approaches of drug dissolution modeling, quantifying the case of reaction-limited dissolution of drugs.

Previous findings from our group based on Monte Carlo simulations indicated that Fickian drug release from Euclidian or fractal matrices can be described with the Weibull function. In this study, the entire drug release kinetics of various published data and experimental data from commercial or prepared controlled release formulations of diltiazem and diclofenac are analyzed using the Weibull function. The exponent of time b of the Weibull function is linearly related to the exponent n of the power law derived from the analysis of the first 60% of the release curves. The value of the exponent b is an indicator of the mechanism of transport of a drug through the polymer matrix. Estimates for b< or =0.75 indicate Fickian diffusion in either fractal or Euclidian spaces while a combined mechanism (Fickian diffusion and Case II transport) is associated with b values in the range 0.75