The Methylazoxymethanol Acetate (MAM-E17) Rat Model: Molecular and Functional Effects in the Hippocampus

Administration of the DNA-alkylating agent methylazoxymethanol acetate (MAM) on embryonic day 17 (E17) produces behavioral and anatomical brain abnormalities, which model some aspects of schizophrenia. This has lead to the premise that MAM rats are a neurodevelopmental model for schizophrenia. However, the underlying molecular pathways affected in this model have not been elucidated. In this study, we investigated the molecular phenotype of adult MAM rats by focusing on the frontal cortex and hippocampal areas, as these are known to be affected in schizophrenia. Proteomic and metabonomic analyses showed that the MAM treatment on E17 resulted primarily in deficits in hippocampal glutamatergic neurotransmission, as seen in some schizophrenia patients. Most importantly, these results were consistent with our finding of functional deficits in glutamatergic neurotransmission, as identified using electrophysiological recordings. Thus, this study provides the first molecular evidence, combined with functional validation, that the MAM-E17 rat model reproduces hippocampal deficits relevant to the pathology of schizophrenia.     

Photodynamic therapy of malignant biliary strictures using meso-tetrahydroxyphenylchlorin

OBJECTIVES: The palliation of patients with malignant bile duct obstruction using metal or plastic biliary stents may be limited by stent occlusion. The aim of this study was to determine the safety and efficacy of endoscopically delivered meso-tetrahydroxyphenyl chlorin photodynamic therapy in the treatment of irresectable malignant biliary strictures and recurrent stent occlusion. METHODS: Thirteen patients with malignant biliary obstruction owing to carcinoma of the biliary tract (n=9), pancreas (n=3) or stomach (n=1), were studied. All had been initially palliated with metal (n=10) or polyethylene (n=3) biliary stents, but presented with recurrent obstructive jaundice because of local tumour progression. Patients received meso-tetrahydroxyphenyl chlorin 0.15 mg/kg intravenously 72 h before endoluminal light activation with an endoscopically placed optical fibre, followed by polyethylene stent insertion. RESULTS: Before photodynamic therapy, patients had a median of three (range 0-5) stent occlusions in the preceding 11 (2-22) months, with a median patency of plastic stents placed inside metal bile duct stents for recurrent stent occlusion of 3.5 (0.5-13) months. After photodynamic treatment, tumour necrosis and/or metal stent recanalization was seen in all patients, with a median of 0 (0-3) stent occlusions during 7 (1-43) months follow-up. The median patency of plastic stents placed inside metal stents after photodynamic therapy was 5 (1-43) months. The median survival after diagnosis and photodynamic therapy administration was 21 (10-56) and 8 (1-43) months, respectively. Photodynamic therapy was generally well tolerated but two patients developed cholangitis within the first week, complicated in one by a fatal liver abscess and two developed haemobilia within 4 weeks of treatment, one of whom died with a gall bladder empyema. CONCLUSION: In patients with malignant biliary obstruction, endoscopically delivered meso-tetrahydroxyphenyl chlorin photodynamic therapy causes efficient tumour necrosis and recanalization of blocked metal stents, but there is a significant risk of complications.     

Effectiveness of a mycoplasma elimination reagent on a mycoplasma-contaminated hybridoma cell line

Mycoplasma contamination in cell culture is a frequently occurring serious limitation to biomedical research, particularly when it affects the irreplaceable cell lines. Although there are few reports of its successful elimination through rigorous protocols, it is the usual practice to destroy the infected cultures. Lately, a physical method using a mycoplasma-eliminating surfactin was described to effectively eliminate mycoplasma contamination from infected cell lines upon single use. We made an attempt using surfactin, an anti-mycoplasma biosurfactant, to eliminate mycoplasma from an extensively infected irreplaceable hybridoma cell line. There were apparent indications of limited elimination, suggesting the possible usefulness of surfactin in achieving total decontamination. However, it was observed that surfactin was toxic to the infected hybridoma cells plated at various cell densities and exposure times. It is suggested that preliminary tests should be performed to determine the cytotoxicity of surfactin with sufficient back-ups of the contaminated cell culture before decontamination is attempted. Additionally, possible ways to enhance its effectiveness are discussed.     

Herbal Excipients in Novel Drug Delivery Systems

The use of natural excipients to deliver the bioactive agents has been hampered by the synthetic materials. However advantages offered by these natural excipients are their being non-toxic, less expensive and freely available. The performance of the excipients partly determines the quality of the medicines. The traditional concept of the excipients as any component other than the active substance has undergone a substantial evolution from an inert and cheap vehicle to an essential constituent of the formulation. Excipients are any component other than the active substance(s) intentionally added to formulation of a dosage form. This article gives an overview of herbal excipients which are used in conventional dosage forms as well as novel drug delivery systems.     

Plasma iron status and lipid peroxidation following thrombolytic therapy for acute myocardial infarction

Summary— Free radical species have been implicated as important agents involved in myocardial ischemic and reperfusion injuries. Superoxide is capable of mobilizing iron from ferritin and the released iron can cause hydroxyl formation from H₂O₂. The aim of this study was to evaluate the time-dependent increase in lipid peroxidation assessed by plasma thiobarbituric acid reactive substances (TBARS) and the relationship between lipid-peroxidation and the iron status. Peripheral venous blood samples were obtained from 17 men with acute myocardial infarction (AMI) before thrombolytic treatment (T0***) and 1, 2, 3, 4, 8, 12, 16, 20, 24 and 48 hours after commencing fibrinolytic treatment. The concentration of TBARS, the parameters of iron metabolism, serum myoglobin, creatine kinase, and creatine kinase-MB were measured. Early reperfusion was judged by regression of sinus tachycardia (ST) elevation and reduction of chest pain. Recanalization of coronary artery was evaluated by a late coronary angiography 24–96 hours after thrombolysis. After thrombolytic therapy, the TBARS level was raised from 2.98 ± 0.80 (T0***) to 4.57 ± 1.24 (peak), and decreased to 2.96 ± 0.40 nmol/mL plasma at T48 (T0 vs peak: P < 0.001, peak vs T48: P < 0.001, TO vs T48: NS). The mean time of the peak was observed at 9.7 ± 7.5 hours. The iron increased significantly from 0.67 ± 0.34 (T0) to 1.15 ± 0.52 mg/L (peak), and returned to the pre-reperfusion to levels: 0.53 ± 0.28 UI/L at T48 (T0 vs peak: P < 0.001, peak vs T48: P < 0.001, TO vs T48: NS). The mean time of the peak was observed at 9.4 ± 7.3 hours. In return, no correlation was found between the increase of plasma creatine-kinase activity, myoglobin and iron or between the biochemical markers and time of fibrinolytic therapy. The results confirmed the importance of the temporal relationship between lipid peroxidation and iron status after thrombolytic therapy. Our results are in agreement with the concept that antioxidant agents used in association with thrombolytic therapy might be useful.     

Direct demonstration that autologous bone marrow transplantation for solid tumors can return a multiplicity of tumorigenic cells

Patients with solid tumors are increasingly being treated by autologous bone marrow transplantation (BMT). Although response rates appear to be increased, disease recurrence is the commonest cause of treatment failure. Whether relapse is entirely due to residual disease in the patient or arises also from infiltrating malignant cells contained in the autologous marrow transplant has not been resolved. If the latter explanation is correct, then purging would be required as part of the transplantation procedure. We used retrovirally mediated transfer of the neomycin-resistance gene to mark BM harvested from eight patients with neuroblastoma in clinical remission. The marked marrow cells were subsequently reinfused as part of an autologous BMT. At relapse, we sought the marker gene in malignant cell populations. Three patients have relapsed, and in each the marker gene was detected by phenotypic and genetic analyses of resurgent malignant cells at medullary and extramedullary sites. Analysis of neuroblast DNA for discrete marker gene integration sites suggested that at least 200 malignant cells, each capable of tumor formation, were introduced with the autologous marrow transplant and contributed to relapse. Thus, autologous BMTs administered to patients with this solid tumor may contain a multiplicity of malignant cells that subsequently contribute to relapse. The marker-gene technique we describe should permit evaluation of the mechanisms of relapse and the efficacy of purging in patients receiving autologous marrow transplantation for other solid tumors that infiltrate the marrow.