Identification of novel glutathione conjugates of terbinafine in liver microsomes and hepatocytes across species.

1. Terbinafine (TBF), a common antifungal agent, has been associated with rare incidences of hepatotoxicity. It is hypothesized that bioactivation of TBF to reactive intermediates and subsequent binding to critical cellular proteins may contribute to this toxicity. In the present study, we have characterized the bioactivation pathways of TBF extensively in human, mouse, monkey, dog and rat liver microsomes and hepatocytes. 2. A total of twenty glutathione conjugates of TBF were identified in hepatocytes; thirteen of these conjugates were also detected in liver microsomes. To the best of our knowledge, only two of these conjugates have been reported previously. The conjugates were categorized into three groups based on their mechanism of formation: (a) alkene/alkyne oxidation followed by glutathione conjugation, with or without N-demethylation, (b) arene oxidation followed by glutathione conjugation, with or without N-demethylation, and (c) N-dealkylation followed by glutathione conjugation of the allylic aldehyde, alcohol and acid intermediates. 3. Differences were observed across species in the contributions of these pathways toward overall metabolic turnover. We conclude that, in addition to the glutathione conjugates known to form by Michael addition to the allylic aldehyde, there are other pathways involving the formation of arene oxides and alkene/alkyne epoxides that may be relevant to the discussion of TBF-mediated idiosyncratic drug reactions.

Variant Philadelphia translocations in chronic myeloid leukemia: A report of five cases.

The t (9;22)(q34;q11) translocation is found in about 90% of the chronic myeloid leukemia patients. About 5-10% of these patients have complex variant translocations involving a third chromosome in addition to chromosomes 9 and 22. We describe five male patients in the chronic myeloid leukemia-chronic phase, with rare variant Philadelphia translocations. All of them had the BCR-ABL fusion gene and responded well to treatment with imatinib mesylate. All the patients are on regular follow-up.

A systematic evaluation of solubility enhancing excipients to enable the generation of permeability data for poorly soluble compounds in Caco-2 model.

The study presented here identified and utilized a panel of solubility enhancing excipients to enable the generation of flux data in the Human colon carcinoma (Caco-2) system for compounds with poor solubility. Solubility enhancing excipients Dimethyl acetamide (DMA) 1 % v/v, polyethylene glycol (PEG) 400 1% v/v, povidone 1% w/v, poloxamer 188 2.5% w/v and bovine serum albumin (BSA) 4% w/v did not compromise Caco-2 monolayer integrity as assessed by trans-epithelial resistance measurement (TEER) and Lucifer yellow (LY) permeation. Further, these excipients did not affect P-glycoprotein (P-gp) mediated bidirectional transport of digoxin, permeabilities of high (propranolol) or low permeability (atenolol) compounds, and were found to be inert to Breast cancer resistant protein (BCRP) mediated transport of cladribine. This approach was validated further using poorly soluble tool compounds, atazanavir (poloxamer 188 2.5% w/v) and cyclosporine A (BSA 4% w/v) and also applied to new chemical entity (NCE) BMS-A in BSA 4% w/v, for which Caco-2 data could not be generated using the traditional methodology due to poor solubility (<1 µM) in conventional Hanks balanced salt solution (HBSS). Poloxamer 188 2.5% w/v increased solubility of atazanavir by >8 fold whereas BSA 4% w/v increased the solubility of cyclosporine A and BMS-A by >2-4 fold thereby enabling permeability as well as efflux liability estimation in the Caco-2 model with reasonable recovery values. To conclude, addition of excipients such as poloxamer 188 2.5% w/v and BSA 4% w/v to HBSS leads to a significant improvement in the solubility of the poorly soluble compounds resulting in enhanced recoveries without modulating transporter-mediated efflux, expanding the applicability of Caco-2 assays to poorly soluble compounds.

Relapsed Hodgkin's Lymphoma Presenting with Isolated Ulcerative Lesion on Base of Tongue.

INTRODUCTION: Primary extra nodal involvement of Hodgkin's lymphoma is very uncommon and previous reports of Hodgkin's lymphoma involving the base of tongue as isolated lesion in relapsed disease are few. CASE PRESENTATION: A 79-years male patient who has diagnosed and treated for stage IV Nodular sclerosis Hodgkin lymphoma 2 years back, now presented with isolated ulcerative lesion in base of tongue which was metabolically active on positron emission tomography scan, suspicious of recurrent disease and was confirmed by routine microscopy and immunohistochemistry of tissue biopsy. CONCLUSION: Extra nodal relapse at base of tongue was an uncommon clinical scenario in natural history of Hodgkin's lymphoma, which can present as an unexpected challenge for diagnosis and management. So we should be aware of this uncommon but unique presentation of Hodgkin's lymphoma.

Rituximab-induced subacute interstitial pneumonitis: a case report and review of literature.

Rituximab is a chimeric anti-CD20 monoclonal antibody used to treat CD20+ non-Hodgkin's lymphoma (NHL). Some pulmonary adverse reactions such as cough, rhinitis, bronchospasm and dyspnea are relatively common. Severe respiratory conditions like cryptogenic organizing pneumonia, interstitial pneumonitis have rarely been reported. We present a case of interstitial pneumonitis in a patient who was treated with R-CHOP for extranodal NHL. He responded to the steroids.

Membranoproliferative glomerulonephritis secondary to chronic myeloid leukemia.

The nephrotic syndrome (NS) is a well documented complication of hematological malignancies. However, chronic myeloid leukemia (CML) is rarely complicated by the NS, and it occurs usually after allogenic stem cell transplantation or interferon alpha therapy for CML. The NS as a complication of untreated CML is also rare. We report a 31-year-old patient who presented with features of The NS. He was diagnosed to have CML one year ago and was on irregular treatment with imatinib mesylate. The renal biopsy and immunofluorescence revealed membrano-proliferative glomerulonephritis type I. The patient was retreated with imatinib mesylate and the NS resolved gradually over three months. This maybe the third case in literature of membrano-proliferative glomerulonephritis associated with CML.

CYP2C9*1B promoter polymorphisms, in linkage with CYP2C19*2, affect phenytoin autoinduction of clearance and maintenance dose.

The commonly prescribed antiepileptic drug phenytoin has a narrow therapeutic range and wide interindividual variability in clearance explained in part by CYP2C9 and CYP2C19 coding variants. After finding a paradoxically low urinary phenytoin metabolite (S)/(R) ratio in subjects receiving phenytoin maintenance therapy with a CYP2C9*1/*1 and CYP2C19*1/*2 genotype, we hypothesized that CYP2C9 regulatory polymorphisms (rPMs), G-3089A and -2663delTG, in linkage disequilibrium with CYP2C19*2 were responsible. These rPMs explained as much as 10% of the variation in phenytoin maintenance dose in epileptic patients, but were not correlated with other patients' warfarin dose requirements or with phenytoin metabolite ratio in human liver microsomes. We hypothesized the rPMs affected CYP2C9 induction by phenytoin, a pregnane X receptor (PXR), and constitutive androstane receptor (CAR) activator. Transfection studies showed that CYP2C9 reporters with wild-type versus variant alleles had similar basal activity but significantly greater phenytoin induction by cotransfected PXR, CAR, and Nrf2 and less Yin Yang 1 transcription factor repression. Phenytoin induction of CYP2C9 was greater in human hepatocytes with the CYP2C9 wild type versus variant haplotype. Therefore, CYP2C9 rPMs affect phenytoin-dependent induction of CYP2C9 and phenytoin metabolism in humans, with an effect size comparable with that for CYP2C9*2 and 2C9*3. These findings may also be relevant to the clinical use of other PXR, CAR, and Nrf2 activators.

Synthesis of deuterium-labelled 5'-O-[N-(Salicyl)sulfamoyl]adenosine (Sal-AMS-d(4)) as an internal standard for quantitation of Sal-AMS.

5'-O-[N-(Salicyl)sulfamoyl]adenosine (Sal-AMS, 1) is a potent inhibitor of the bifunctional enzyme salicyl-AMP ligase in Mycobacterium tuberculosis. This inhibitor acts by disrupting the biosynthesis of the mycobactin siderophores that are essential for the process of iron acquisition. To aid with in vitro metabolism and in vivo pharmacokinetic studies of Sal-AMS, a stable deuterium-labelled Sal-AMS analog (Sal-AMS-d(4)) was synthesized. This deuterium-labelled analog was used as an internal standard to conduct in vitro plasma and microsomal stability studies. Sal-AMS was found to be stable for 24 h in human plasma and 1 h in human liver microsomes at 37 degrees C.

Embryonal rhabdomyosarcoma of the chest wall: a case report and review of the literature.

Embryonal rhabdomyosarcoma is a soft-tissue sarcoma which has a predilection for the head and neck area, genitourinary tract and the extremities. We report a rare case of embryonal rhabdomyosarcoma of the chest wall in an 8-year-old girl, presenting as a destructive tumor in the rib and clinically and radiologically mimicking Ewing's sarcoma. Histopathological examination showed a small round cell tumor. Immunohistochemically, the positivity for muscle markers desmin and myogenin in the tumor cells proved to be useful for making a definitive diagnosis of embryonal rhabdomyosarcoma. Cytogenetic analysis revealed a high level of aneuploidy in the tumor cells, with double-minutes and additional chromosomal structural aberrations. The patient is responding well to chemotherapy.

Enhanced transformation of tnt by tobacco plants expressing a bacterial nitroreductase.

The manufacture, disposal, and detonation of explosives have resulted in the pollution of large tracts of land and groundwater. Historically, 2,4,6-trinitrotoluene (TNT) is the most widely used military explosive and is toxic to biological systems and recalcitrant to degradation. To examine the feasibility of enhancing the ability of plants to detoxify the explosive TNT, we created transgenic tobacco (Nicotiana tabacum) constitutively expressing the nsfI nitroreductase gene from Enterobacter cloacae. The product of TNT reduction by the nitroreductase was found to be 4-hydroxylamino-2,6-dinitrotoluene (4-HADNT). Characterization of the transgenic lines in sterile, aqueous conditions amended with TNT demonstrated that these plants were able to remove all of the TNT from the medium at an initial concentration of 0.5 mM (113 mg L(-1)) TNT. In contrast, growth was suppressed in wild-type plants at 0.1 mM (23 mg L(-1)). Following uptake, transgenic seedlings transformed TNT predominantly to 4-HADNT and its high levels appeared to correlate with enhanced tolerance and transformation of TNT. Transformation products of TNT were subsequently conjugated to plant macromolecules to a greater degree in transgenic tobacco, indicating enhanced detoxification compared to the wild type.