Effects of rapamycin treatment on pancreatic fibrosis, cellular apoptosis and oxidative stress in experimental chronic pancreatitis model

PURPOSE

Rapamycin reduces hepatic fibrosis by inhibiting hepatic stellate cell activation. The present study investigated whether rapamycin treatment could modify the degree of fibrosis, cellular apoptosis and oxidative stress (OS) in an experimental model of CP.

METHODS

Fifty-five male, Sprague-Dawley rats weighing 200-400g were randomized into four groups. CP was induced by intraductal trinitrobenzene sulfonic acid (TNBS) infusion in group A (n = 15) and group B (n = 15). Group C (n = 15) received intraductal TNBS and was killed for histologic confirmation at four weeks. Group D (n = 10) received intraductal saline instead of TNBS. Group A and group D received oral rapamycin (2 mg/kg/d) for two weeks after CP was induced while group B received oral tap water instead of rapamycin. Blood and pancreatic tissue specimens were collected and oxidative stress parameters, fibrosis and cellular apoptosis were determined.

RESULTS

Tissue and blood malondialdehyde (MDA) levels were significantly lower in rapamycin treated group compared to controls (p < 0.001). Superoxide dismutase (SOD) and glutathion peroxidase (GSH-Px) activities were also significantly higher in the active treatment group (p < 0.001 for both). Tissue and blood MDA, SOD, GSH-Px measurements was similar in rapamycin group and pancreatic cannulation group (p > 0.05). Histopathologic fibrosis scores were similar in rapamycin and control groups. Apoptotic cell counts tended to be lower in rapamycin treated animals.

CONCLUSIONS

Administration of rapamycin alleviated OS and, in part, prevented apoptotic cell death in experimental CP, but did not reduce fibrosis.

Antiretroviral drugs induce oxidative stress and neuronal damage in the central nervous system

HIV-associated neurocognitive disorder (HAND), characterized by a wide spectrum of behavioral, cognitive, and motor dysfunctions, continues to affect approximately 50 % of HIV(+) patients despite the success of combination antiretroviral drug therapy (cART) in the periphery. Of note, potential toxicity of antiretroviral drugs in the central nervous system (CNS) remains remarkably underexplored and may contribute to the persistence of HAND in the cART era. Previous studies have shown antiretrovirals (ARVs) to be neurotoxic in the peripheral nervous system in vivo and in peripheral neurons in vitro. Alterations in lipid and protein metabolism, mitochondrial damage, and oxidative stress all play a role in peripheral ARV neurotoxicity. We hypothesized that ARVs also induce cellular stresses in the CNS, ultimately leading to neuronal damage and contributing to the changing clinical and pathological picture seen in HIV-positive patients in the cART era. In this report, we show that ARVs are neurotoxic in the CNS in both pigtail macaques and rats in vivo. Furthermore, in vitro, ARVs lead to accumulation of reactive oxygen species (ROS), and ultimately induction of neuronal damage and death. Whereas ARVs alone caused some activation of the endogenous antioxidant response in vitro, augmentation of this response by a fumaric acid ester, monomethyl fumarate (MMF), blocked ARV-induced ROS generation, and neuronal damage/death. These findings implicate oxidative stress as a contributor to the underlying mechanisms of ARV-induced neurotoxicity and will provide an access point for adjunctive therapies to complement ARV therapy and reduce neurotoxicity in this patient population.

Calpain-mediated degradation of MDMx/MDM4 contributes to HIV-induced neuronal damage

Neuronal damage in HIV-associated Neurocognitive Disorders (HAND) has been linked to inflammation induced by soluble factors released by HIV-infected, and non-infected, activated macrophages/microglia (HIV M/M) in the brain. It has been suggested that aberrant neuronal cell cycle activation determines cell fate in response to these toxic factors. We have previously shown increased expression of cell cycle proteins such as E2F1 and phosphorylated pRb in HAND midfrontal cortex in vivo and in primary neurons exposed to HIV M/M supernatants in vitro. In addition, we have previously shown that MDMx (also referred to as MDM4), a negative regulator of E2F1, was decreased in the brain in a primate model of HIV-induced CNS neurodegeneration. Thus, we hypothesized that MDMx provides indirect neuroprotection from HIV-induced neurodegeneration in our in vitro model. In this report, we found significant reductions in MDMx protein levels in the mid-frontal cortex of patients with HAND. In addition, treatment of primary rat neuroglial cultures with HIV M/M led to NMDA receptor- and calpain-dependent degradation of MDMx and decreased neuronal survival, while overexpression of MDMx conferred partial protection from HIV M/M toxicity in vitro. Further, our results demonstrate that MDMx is a novel and direct calpain substrate. Finally, blocking MDMx activity led to neuronal death in vitro in the absence of toxic stimulus, which was reversed by calpain inhibition. Overall, our results indicate that MDMx plays a pro-survival role in neurons, and that strategies to stabilize and/or induce MDMx can provide neuroprotection in HAND and in other neurodegenerative diseases where calpain activation contributes to neuropathogenesis.

The protective effects of taurine on experimental acute pancreatitis in a rat model

The aim of this study was to investigate the protective effects of taurine (Tau) on experimental acute pancreatitis (AP) in a rat model by measuring cytokines and oxidant stress markers.

Forty rats were randomly divided into four groups: sham, AP, Tau and AP + Tau. AP was induced with sodium taurocholate. No treatment was given to the AP. All rats were killed 5 days later. Pancreatic tissues of rats and blood samples were obtained.

Tau treatment significantly decreased serum amylase activity ( p < 0.001), total injury score ( p < 0.001), malondialdehyde levels ( p < 0.001) and myeloperoxidase (MPO) activity ( p < 0.001). There was no significant difference between the Tau and AP + Tau groups in serum and pancreatic tumor necrosis factor-α, interleukin (IL)-1β and IL-6 levels ( p = 1.000). Histopathologic scores in the AP + Tau and Tau groups were significantly lower compared with the AP group (both p < 0.001).

These results showed that Tau reduces lipid peroxidation, amylase and MPO activities and the concentrations of proinflammatory cytokines secondary to AP and also increases superoxide dismutase and glutathione peroxidase activities in rats with sodium taurocholate-induced AP. It also has a marked ameliorative effect at histopathologic lesions. With these effects, Tau protects the cells from oxidative damage, reduces inflammation and promotes regression of pancreatic damage.

Activation status of integrated stress response pathways in neurones and astrocytes of HIV-associated neurocognitive disorders (HAND) cortex

C. Akay, K. A. Lindl, N. Shyam, B. Nabet, Y. Goenaga‐Vazquez, J. Ruzbarsky, Y. Wang, D. L. Kolson and K. L. Jordan‐Sciutto (2012) Neuropathology and Applied Neurobiology38, 175–200

Activation status of integrated stress response pathways in neurones and astrocytes of HIV‐associated neurocognitive disorders (HAND) cortex

Aims: Combined anti‐retroviral therapy (cART) has led to a reduction in the incidence of HIV‐associated dementia (HAD), a severe motor/cognitive disorder afflicting HIV(+) patients. However, the prevalence of subtler forms of neurocognitive dysfunction, which together with HAD are termed HIV‐associated neurocognitive disorders (HAND), continues to escalate in the post‐cART era. The microgliosis, astrogliosis, dendritic damage, and synaptic and neuronal loss observed in autopsy cases suggest an underlying neuroinflammatory process, due to the neurotoxic factors released by HIV‐infected/activated macrophages/microglia in the brain, might underlie the pathogenesis of HAND in the post‐cART era. These factors are known to induce the integrated stress response (ISR) in several neurodegenerative diseases; we have previously shown that BiP, an indicator of general ISR activation, is upregulated in cortical autopsy tissue from HIV‐infected patients. The ISR is composed of three pathways, each with its own initiator protein: PERK, IRE1α and ATF6. Methods: To further elucidate the specific ISR pathways activated in the central nervous system of HAND patients, we examined the protein levels of several ISR proteins, including ATF6, peIF2α and ATF4, in cortical tissue from HIV‐infected patients. Results: The ISR does not respond in an all‐or‐none fashion in HAND, but rather demonstrates a nuanced activation pattern. Specifically, our studies implicate the ATF6 pathway of the ISR as a more likely candidate than the PERK pathway for increases in BiP levels in astrocytes. Conclusion: These findings begin to characterize the nature of the ISR response in HAND and provide potential targets for therapeutic intervention in this disease.

Association of GPX1 polymorphism, GPX activity and prostate cancer risk

Prostate cancer is the second most common cancer in men worldwide. Although the aetiology of this disease remains largely unclear, several lines of evidence suggest that oxidative stress plays a role in prostate carcinogenesis. The antioxidant enzyme glutathione peroxidase 1 (GPX1) is part of the enzymatic antioxidant defence, preventing oxidative damage to DNA, proteins and lipids by detoxifying hydrogen and lipid peroxides that may contribute to prostate cancer development. Some studies indicate an association between GPX1 Pro198Leu polymorphism and an increased risk of cancer. The purpose of the present study was to determine the possible association of GPX1 Pro198Leu polymorphism and erythrocyte GPX activity with the risk of developing prostate cancer and to clarify whether erythrocyte GPX activity levels were correlated with the GPX1 Pro198Leu genotype in the Turkish population. The GPX1 Pro198Leu genotype was determined in 33 prostate cancer patients and 91 control individuals. As evident from our results, there was no difference between genotype and/or allele frequencies in prostate cancer patients and controls. No significant difference was found in GPX1 genotype or allele frequency between aggressive and non-aggressive prostate cancer patients. It can be suggested with these findings that individual susceptibility of prostate cancer may be modulated by GPX1 polymorphism, but it needs further studies.

Site-specific hyperphosphorylation of pRb in HIV-induced neurotoxicity

HIV-Associated Neurocognitive Disorder (HAND) remains a serious complication of HIV infection, despite combined Anti-Retroviral Therapy (cART). Neuronal dysfunction and death are attributed to soluble factors released from activated and/or HIV-infected macrophages. Most of these factors affect the cell cycle machinery, determining cellular outcomes even in the absence of cell division. One of the earliest events in cell cycle activation is hyperphosphorylation of the retinoblastoma protein, pRb (ppRb). We and others have previously shown increased ppRb expression in the CNS of patients with HIV encephalitis (HIVE) and in neurons in an in vitro model of HIV-induced neurodegeneration. However, trophic factors also lead to an increase in neuronal ppRb with an absence of cell death, suggesting that, depending on the stimulus, hyperphosphorylation of pRb can have different outcomes on neuronal fate. pRb has multiple serines and threonines targeted for phosphorylation by distinct kinases, and we hypothesized that different stimuli may target separate sites for phosphorylation. Thus, to determine whether pRb is differentially phosphorylated in response to different stimuli and whether any of these sites is preferentially phosphorylated in association with HIV-induced neurotoxicity, we treated primary rat mixed cortical cultures with trophic factors, BDNF or RANTES, or with the neurotoxic factor, N-methyl-d-aspartate (NMDA), or with supernatants containing factors secreted by HIV-infected monocyte-derived macrophages (HIV-MDM), our in vitro model of HIV-induced neurodegeneration. We found that, while BDNF and RANTES phosphorylated serine807/811 and serine608 in vitro, treatment with HIV-MDM did not, even though these trophic factors are components of HIV-MDM. Rather, HIV-MDM targets a specific phosphorylation site, serine795, of pRb for phosphorylation in vitro and this ppRb isoform is also increased in HIV-infected brains in vivo. Further, overexpression of a nonphosphorylatable pRb (ppRb S795A) attenuated HIV-MDM-induced neurotoxicity. These findings indicate that HIV-infection in the brain is associated with site-specific hyperphosphorylation of pRb at serine795, which is not induced by other tested stimuli, and that this phosphorylation contributes to neuronal death in this disease, demonstrating that specific pRb sites are differentially targeted and may have diverse impacts on the viability of post-mitotic neurons.

Parallel high throughput neuronal toxicity assays demonstrate uncoupling between loss of mitochondrial membrane potential and neuronal damage in a model of HIV-induced neurodegeneration

Neurocognitive deficits seen in HIV-associated neurocognitive disorders (HANDs) are attributed to the release of soluble factors from CNS-resident, HIV-infected and/or activated macrophages and microglia. To study HIV-associated neurotoxicity, we used our in vitro model in which primary rat neuronal/glial cultures are treated with supernatants from cultured human monocyte-derived macrophages, infected with a CNS-isolated HIV-1 strain (HIV-MDM). We found that neuronal damage, detected as a loss of microtubule-associated protein-2 (MAP2), begins as early as 2h and is preceded by a loss of mitochondrial membrane potential (Δψ(m)). Interestingly, inhibitors of calpains, but not inhibitors of caspases, blocked MAP2 loss, however neither type of inhibitor prevented the loss of Δψ(m). To facilitate throughput for these studies, we refined a MAP2 cell-based-ELISA whose data closely compare with our standardized method of hand counting neurons. In addition, we developed a tetramethyl rhodamine methyl ester (TMRM)-based multi-well fluorescent plate assay for the evaluation of whole culture Δψ(m). Together, these findings indicate that calpain activation and loss of Δψ(m) may be parallel pathways to death in HIV-MDM-treated neurons and also demonstrate the validity of plate assays for assessing multiple experimental parameters as is useful for screening neurotherapeutics for neuronal damage and death.

Improved mobilization of peripheral blood CD34+ cells and dendritic cells by AMD3100 plus granulocyte-colony-stimulating factor in non-Hodgkin's lymphoma patients

AMD3100 is a drug capable of mobilizing peripheral blood stem cells (PBSCs) in donors and in cancer patients as a single agent or in combination with granulocyte-colony-stimulating factor (G-CSF). We initiated a phase II study of 11 refractory or relapsed non-Hodgkin's lymphoma (NHL) patients, receiving 16 microg/kg daily of G-CSF for 4 days followed by 240 microg/kg of AMD3100 given subcutaneously on a new schedule of 9-10 h before apheresis collection on day 5. Our aims were to assess the effect of AMD3100 on the mobilization of CD34+ cells, dendritic cells (DCs) and lymphoma cells. Administration of G-CSF and AMD3100 were continued daily until >or=2 x 10(6) CD34+ cells/kg were collected. Adequate collection of the target of CD34+ cells was achieved in all but 1 patient within 2 days, and 10/11 patients were transplanted within 2 months. All transplanted patients engrafted with a mean of 10 and 12 days for neutrophils and platelets, respectively. Addition of AMD3100 to G-CSF resulted with >2.5-fold increase in CD34+ cells/microl (p = 0.0001) and in a >2-fold increase in pDC1 and pDC2 cells/microl (p = 0.003). Adverse events related to AMD3100 were minimal. AMD3100 was generally safe and improved PBSC and DC cell mobilization with no apparent contamination of lymphoma cells.

Expression of the endoplasmic reticulum stress response marker, BiP, in the central nervous system of HIV-positive individuals

The prevalence of HIV-associated neurocognitive impairment (NCI), which includes HIV-associated dementia (HAD) and minor cognitive and motor disorder (MCMD), has been increasing. HIV-infected and/or activated macrophages/microglia in the brain initiate the neurodegeneration seen in HIV-associated NCI via soluble neurotoxic mediators, including reactive oxygen species, viral proteins and excitotoxins. Neurotoxic factors released by macrophages/microglia injure neurones directly and alter astrocytic homeostatic functions, which can lead to excitotoxicity and oxidative stress-mediated neuronal injury. Often, cells respond to oxidative stress by initiating the endoplasmic reticulum (ER) stress response. Thus, we hypothesize that ER stress response is activated in HIV-infected cortex. We used immunofluorescence and immunoblotting to assess expression patterns of the ER stress proteins, BiP and ATF6, in HIV-positive cortical autopsy tissue. Additionally, we performed immunofluorescence using cell type-specific markers to examine BiP staining in different cell types, including neurones, astrocytes and macrophages/microglia. We observed a significant increase in BiP expression by both immunoblotting and immunofluorescence in HIV-positive cortex compared with control tissue. Additionally, phenotypic analysis of immunofluorescence showed cell type-specific increases in BiP levels in neurones and astrocytes. Further, ATF-6beta, an ER stress response initiator, is up-regulated in the same patient group, as assessed by immunoblotting. These results suggest that ER stress response is activated in HIV-infected cortex. Moreover, data presented here indicate for the first time that numbers of macrophages/microglia increase in brains of MCMD patients, as has been observed in HAD.

Activation of cyclin-dependent kinase 5 by calpains contributes to human immunodeficiency virus-induced neurotoxicity

Although the specific mechanism of neuronal damage in human immunodeficiency virus (HIV) -associated dementia is not known, a prominent role for NMDA receptor (NMDAR)-induced excitotoxicity has been demonstrated in neurons exposed to HIV-infected/activated macrophages. We hypothesized NMDAR-mediated activation of the calcium-dependent protease, calpain, would contribute to cell death by induction of cyclin-dependent kinase 5 (CDK5) activity. Using an in vitro model of HIV neurotoxicity, in which primary rat cortical cultures are exposed to supernatants from primary human HIV-infected macrophages, we have observed increased calpain-dependent cleavage of the CDK5 regulatory subunit, p35, to the constitutively active isoform, p25. Formation of p25 is dependent upon NMDAR activation and calpain activity and is coincident with increased CDK5 activity in this model. Further, inhibition of CDK5 by roscovitine provided neuroprotection in our in vitro model. Consistent with our observations in vitro, we have observed a significant increase in calpain activity and p25 levels in midfrontal cortex of patients infected with HIV, particularly those with HIV-associated cognitive impairment. Taken together, our data suggest calpain activation of CDK5, a pathway activated in HIV-infected individuals, can mediate neuronal damage and death in a model of HIV-induced neurotoxicity.

Arsenic trioxide induces p53-dependent apoptotic signals in myeloma cells with SiRNA-silenced p53: MAP kinase pathway is preferentially activated in cells expressing inactivated p53

Mutations in p53 are the most common genetic abnormality in cancers. Arsenic trioxide (ATO) is an effective chemotherapeutic agent for the treatment of acute promyelocytic leukemia (APL) and is being tested in phase II studies in various types of cancers. We have shown that ATO is a potent inducer of apoptosis in multiple myeloma cells, engaging primarily the intrinsic apoptotic pathway in cells expressing w.t. p53 and the extrinsic apoptotic pathway in cells expressing mutant p53. To further establish the differential apoptotic signals of ATO in relation to p53 functional status we studied the activation of the intrinsic and the extrinsic apoptotic pathways in IM9 myeloma cells expressing w.t. p53 following silencing of p53 and p21 with the corresponding SiRNAs-GFP constructs. In untransfected cells or in cells transfected with GFP-empty vector construct we observed weak apoptosis concomitant with mild depolarization of mitochondrial membrane, depletion of reduced glutathione and release of cytochrome c. Following silencing of p53 or p21 we observed extensive apoptosis concomitant with extensive depolarization of mitochondrial membrane and depletion of reduced glutathione. We also observed in these cells activation of the extrinsic apoptotic pathway through upregulation of APO2/TRAIL and APO2/TRAIL-R2, activation of caspase 8, degradation of FLIP-L and release of apoptosis inducing factors from mitochondria, instead of cytochrome c. In addition, we observed marked activation of the MAP kinase pathway and dephosphorylation of Akt in p53 or p21 silenced cells. Hence, silencing of p53 or p21 in IM9 myeloma cells results in diversion of apoptosis to the extrinsic pathway and sensitization of myeloma cells to ATO.

Granulocyte Colony-Stimulating Factor Mobilizes More Dendritic Cell Subsets Than Granulocyte-Macrophage Colony-Stimulating Factor with No Polarization of Dendritic Cell Subsets in Normal Donors

Dendritic cells (DCs) are effective antigen-presenting cells. We hypothesized that increasing the DC populations in donor lymphocyte infusions (DLIs) may augment the graft versus malignancy effect, particularly if granulocyte-macrophage colony-stimulating factor (GM-CSF) mobilization resulted in increased precursor dendritic cell (pDC) 1 cells. Mature DCs, pDC1 cells, pDC2 cells, and CD34(+) cells from the same donor were compared after granulocyte colony-stimulating factor (G-CSF) mobilized peripheral blood stem cell collections and GM-CSF mobilized DLI collections. Mobilization with G-CSF resulted in up to a 10-fold larger number of CD34(+) cells per kg and a 3-5-fold larger number of mature DCs, pDC1 cells, and pDC2 cells within the same donor compared with GM-CSF. The ratio of pDC1 to pDC2 in each donor remained constant with either cytokine. In this small sample of normal donors, it appears that G-CSF mobilizes more CD34(+) cells, mature DCs, pDC1 cells, and pDC2 cells within the same donor than does GM-CSF, with no significant polarization by G-CSF or GM-CSF for either pDC1 or pDC2 cells.

No Polarization of Type 1 or Type 2 Precursor Dendritic Cells in Peripheral Blood Stem Cell Collections of Non-Hodgkin's Lymphoma Patients Mobilized with Cyclophosphamide Plus G-CSF, GM-CSF, or GM-CSF Followed by G-CSF

Dendritic cells (DCs) are the most efficient antigen-presenting cells and play a role in immune reconstitution after autologous transplantation. Recent reports suggest that mobilization with granulocyte colony-stimulating factor (G-CSF) containing regimens polarizes DCs into pDC2, which could potentially result with increased Th2 response and decreased graft-versus-host disease (GVHD) in allogeneic transplantation and with decreased cytotoxic Th1 response and graft versus tumor effect, which in autologous transplantation could translate into increased relapse rate. Previously, we have shown that non-Hodgkin's lymphoma (NHL) patients receiving cyclophosphamide (CTX) plus granulocyte- macrophage (GM)-CSF, G-CSF or GM-CSF followed by G-CSF for stem cell collection, mobilize up to five-fold more mature CD80(+) DCs compared to CTX plus G-CSF mobilized patients. Here, we analyzed samples from the same study for the number of pDC1 and pDC2 subsets in blood and apheresis products obtained from these patients. Samples from 29 patients were collected. Patients mobilized with CTX plus G-CSF collected a mean of 1.2 +/- 0.4 x 10(6) pDC1/kg per day and 2.2 +/- 1 x 10(6) pDC2/kg per day, whereas patients mobilized with CTX plus GM-CSF collected a mean of 1.1 +/- 0.5 x 10(6) pDC1 and 1.5 +/- 0.9 x 10(6) pDC2/kg per day. Patients mobilized with CTX plus GM-CSF followed by G-CSF collected 2.5 +/- 1.1 x 10(6) pDC1 and 2 +/- 0.5 x 106 pDC2/kg per day, with significantly higher levels of pDC1 +/- pDC2 cells. No significant difference was observed in pDC1/pDC2 ratio between the three mobilization arms. Patients mobilized with the GM-CSFcontaining regimen had a higher probability for survival compared to patients receiving G-CSF alone (median of 55 months vs. 15 months; p = 0.02). These results support the hypothesis that higher levels of DCs in the graft might be associated with prolonged survival of autotransplanted NHL patients. Further similar studies are merited in a larger population of NHL patients.

Arsenic trioxide: an anti cancer missile with multiple warheads

The proven efficacy of ATO in the treatment of APL and the emerging importance of ATO in other diseases prompted extensive studies of the mechanisms of action of ATO in APL and in other types of cancers. In this review we will focus on downstream events in ATO-induced intrinsic and extrinsic apoptotic pathways with an emphasis on the role of pro-apoptotic and anti-apoptotic proteins and the role of p53 in ATO-induced apoptosis including its effect on cell cycle, its anti-mitotic effect and the role of apoptosis inducing factors (AIF) in ATO-induced apoptosis, chromatin condensation and nuclear fragmentation in myeloma cells as a model.

Antioxidant system activation in prostate cancer

The activities of glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) and the levels of copper, zinc, and malondialdehyde were determined in 21 age-, sex-, and body-mass-index-matched prostate cancer patients; 50 patients diagnosed with benign prostatic obstruction (BPO) were compared to 50 healthy male subjects acting as controls. The patients were divided into two groups depending on the stage of the disease (group 1 [organ-confined] and group II [advanced disease]) and into three subgroups according to differentiation criteria: subgroup A (n = 5, Gleason sum 2-4, well differentiated); subgroup B (n = 9, Gleason sum 5-7, moderately differentiated), and subgroup C (n = 7, Gleason sum 8-10, poorly differentiated). The MDA levels were higher and the antioxidant activity and Zn levels lower in the prostate cancer groups than in the healthy control and BPO groups. These results confirm the value of therapies aimed at increasing the antioxidant capacity and encourage the use of plasma and erythrocyte Zn levels in the differential diagnosis of BPO and prostate cancer. The MDA levels can be used in the diagnosis and follow-up of prostate cancer.

Arsenic trioxide and paclitaxel induce apoptosis by different mechanisms

Arsenic trioxide (ATO) and paclitaxel (TAXOL) are effective in the treatment of various types of cancers. Both drugs induce G2/M arrest. We have previously shown that ATO is a potent inducer of apoptosis in myeloma cells expressing mutant p53 engaging both the intrinsic and extrinsic apoptotic pathways. Here we compared the effect of ATO and TAXOL on myeloma cells expressing mutant p53 and varying levels of Bcl-2. ATO rapidly induced Apo2/TRAIL, activation of caspase 8, cleavage of BID, depolarization of mitochondrial membrane (MM) and release of AIF from mitochondria in a Bcl-2 independent fashion. Apoptosis was associated with early formation of ring-like perinuclear condensed chromatin colocalized with AIF. In contrast, paclitaxel-induced apoptosis MM depolarization, cytochrome C release and activation of caspase 9 were all blocked by Bcl-2. Apoptosis was associated with a random chromatin condensation and nuclear fragmentation with no early involvement of AIF.

Arsenic trioxide and paclitaxel induce apoptosis by different mechanisms

Arsenic trioxide (ATO) and paclitaxel (TAXOL) are effective in the treatment of various types of cancers. Both drugs induce G2/M arrest. We have previously shown that ATO is a potent inducer of apoptosis in myeloma cells expressing mutant p53 engaging both the intrinsic and extrinsic apoptotic pathways. Here we compared the effect of ATO and TAXOL on myeloma cells expressing mutant p53 and varying levels of Bcl-2. ATO rapidly induced Apo2/TRAIL, activation of caspase 8, cleavage of BID, depolarization of mitochondrial membrane (MM) and release of AIF from mitochondria in a Bcl-2 independent fashion. Apoptosis was associated with early formation of ring-like perinuclear condensed chromatin colocalized with AIF. In contrast, paclitaxel-induced apoptosis MM depolarization, cytochrome C release and activation of caspase 9 were all blocked by Bcl-2. Apoptosis was associated with a random chromatin condensation and nuclear fragmentation with no early involvement of AIF.

Oxidative stress in patients undergoing high-dose chemotherapy plus peripheral blood stem cell transplantation

Chemotherapy and radiation therapy are associated with increased formation of reactive oxygen species and depletion of critical plasma and tissue antioxidants. In patients undergoing high-dose chemotherapy, the plasma antioxidant concentration has been shown to decrease. However, these studies in which the oxidative stress status were investigated have a small number of patients and they are heterogeneous. In this study, the changes in certain trace elements together with oxidative stress parameters were investigated in 36 patients who had undergone autologous stem cell transplantation because of solid and hematological malignancies. Blood samples of the patients were examined before the high-dose chemotherapy (baseline), before stem cell transplantation (day -1), and after stem cell transplantation on day 1, 3, and 6. Erythrocyte zinc, silver, and iron levels were measured by atomic absorption spectrophotometry; malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) levels were measured by UV-vis spectrophotometry. After high-dose chemotherapy, significant increases in the levels of MDA, GSH-Px, and SOD were observed. On the other hand, Cu levels remained the same while the levels of erythrocyte Zn and Fe were increased. Significant correlation was observed among MDA, GSH-Px, and SOD (p<0.05). High-dose chemotherapy gives rise to an increase in the oxidative stress and the reactive oxygen species. Standard parenteral nutrition protocols were found to be insufficient to lower this stress.

Effect of hyperbaric oxygen on experimental acute distal colitis

It has been demonstrated that hyperbaric oxygen (HBO) is useful as an adjunctive therapy for Crohn's disease. However, its effects on ulcerative colitis have not been investigated. In the present study, HBO was tested for acetic acid-induced colitis, and antioxidant systems were evaluated to clarify its possible mode of action. Thirty-six Sprague-Dawley rats were randomly divided into three groups: sham control (Group I), colitis induced by acetic acid without any therapy (Group II), colitis induced by acetic acid and treated with HBO (Group III). HBO was given for 5 days, 2 sessions per day at 2.5-fold absolute atmosphere pressure (ATA) for a period of 90 min in rats in which colitis had been induced (Group III). Rats were sacrificed on the 5th day after the procedure. Superoxide dismutase (SOD), malondialdehyde (MDA) and glutathione peroxidase (GSH Px) activity were measured in the intestinal tissue and erythrocyte lysate. MDA and GSH Px were also determined in the plasma. Whereas MDA levels in erythrocyte, plasma and intestinal tissue were decreased, the levels of GSH Px and SOD were significantly increased in Group III as compared to those of Group II. The results of our study suggest that hyperbaric oxygen therapy has beneficial effects on the course of experimental distal colitis and that antioxidant systems may be involved in its mode of action.

Effect of hyperbaric oxygen on experimental acute distal colitis

It has been demonstrated that hyperbaric oxygen (HBO) is useful as an adjunctive therapy for Crohn's disease. However, its effects on ulcerative colitis have not been investigated. In the present study, HBO was tested for acetic acid-induced colitis, and antioxidant systems were evaluated to clarify its possible mode of action. Thirty-six Sprague-Dawley rats were randomly divided into three groups: sham control (Group I), colitis induced by acetic acid without any therapy (Group II), colitis induced by acetic acid and treated with HBO (Group III). HBO was given for 5 days, 2 sessions per day at 2.5-fold absolute atmosphere pressure (ATA) for a period of 90 min in rats in which colitis had been induced (Group III). Rats were sacrificed on the 5th day after the procedure. Superoxide dismutase (SOD), malondialdehyde (MDA) and glutathione peroxidase (GSH Px) activity were measured in the intestinal tissue and erythrocyte lysate. MDA and GSH Px were also determined in the plasma. Whereas MDA levels in erythrocyte, plasma and intestinal tissue were decreased, the levels of GSH Px and SOD were significantly increased in Group III as compared to those of Group II. The results of our study suggest that hyperbaric oxygen therapy has beneficial effects on the course of experimental distal colitis and that antioxidant systems may be involved in its mode of action.

Mobilization of Myeloma Cells Involves SDF-1/CXCR4 Signaling and Downregulation of VLA-4

Adhesion molecules and stromal cell-derived factor-1 (SDF-1)/CXCR4 signaling play key roles in homing and mobilization of hematopoietic stem cells (HSC). Active signaling through SDF-1/CXCR4 and upregulation of adhesion molecules are required for homing, whereas downregulation of adhesion molecules and disruption of SDF-1/CXCR4 signaling are required for mobilization of HSC. We studied the surface expression of CXCR4 very late activation antigen (VLA)-4 and VLA-5 on myeloma cells mobilized with cyclophosphamide and GM-CSF in 12 multiple myeloma patients undergoing HSC mobilization for autologous transplantation. We also studied the plasma levels of SDF-1 in apheresis collection of these patients. We observed a statistically significant decrease in the levels of SDF-1 and surface expression of CXCR4 on myeloma cells in four consecutive apheresis collections compared with premobilization bone marrow specimens. We also observed a statistically significant decrease in surface expression of VLA-4 in myeloma cells in the apheresis collections compared with premobilization bone marrow samples. Furthermore, myeloma cells derived from apheresis collections had decreased adhesion and trans-stromal migration in response to SDF-1, which could be reversed by short incubation with interleukin-6. Hence, mobilization of myeloma cells involves SDF-1/CXCR4 signaling and downregulation of VLA-4.

The effect of hyperbaric oxygen treatment on oxidative stress in experimental acute necrotizing pancreatitis

Various protocols may be used for acute pancreatitis treatment. Recently, the benefit of hyperbaric oxygen (HBO) has been demonstrated. To clarify the mechanism of HBO on the process of the acute pancreatitis, we determined the levels of antioxidant enzymes in an acute pancreatitis model. Forty-five Sprague-Dawley rats were randomly divided into three groups: Group I: sham group (n=15), Group II: pancreatitis group (n=15), Group III: pancreatitis group undergoing HBO therapy (n=15). HBO was applied postoperatively for 5 days, two sessions per day at 2.5 fold absolute atmospheric pressure (ATA) for 90 min. Superoxide dismutase (Cu/Zn-SOD), malondialdehyde (MDA), and glutathione peroxidase (GSH Px) activity were measured in pancreatic tissue and erythrocyte lysate. MDA and GSH Px were also determined in plasma. In addition, amylase levels were measured in the serum. While serum amylase levels and MDA values in erythrocyte, plasma and pancreatic tissue were decreased, the levels of GSH Px and SOD were found to be significantly increased in the Group III as compared to those of the Group II. The findings of our study suggest that HBO has beneficial effects on the course of acute pancreatitis and this effect may occur through the antioxidant systems.

Arsenic trioxide selectively induces early and extensive apoptosis via the APO2/caspase-8 pathway engaging the mitochondrial pathway in myeloma cells with mutant p53

Arsenic trioxide (ATO) is effective in the treatment of acute promyelocytic leukemia (APL) and induces apoptosis in APL cells and in a great variety of other cancer cells. We have previously shown that ATO induces apoptosis in myeloma cells in two different modes depending on p53 status in the cells. In cells expressing mutated p53, ATO induced, G2/M arrest and activation caspase 8 and 3 and rapid and extensive apoptosis. Myeloma cells expressing w.t. p53, ATO induced G1 arrest and delayed apoptosis with activation of caspase 9 and 3. APO2/TRAIL receptor expression was induced in both cell types and APO2/TRAIL synergized with ATO in the induction of apoptosis. Here we tested the effect of ATO on mitochondrial membrane potential (MMP) in myeloma cells expressing mutated or w.t. p53. In myeloma cells expressing mutated p53, depolarization of MMP occurred early, concomitant with induction of APO2/TRAIL, activation of BID and release of AIF, preceding apoptosis. However, in cells expressing w.t. p53, APO2/TRAIL is not induced, BID is not cleaved and depolarization of MMP occurs concurrently with cytochrome c release and apoptosis. These results explain the greater sensitivity to ATO of cells with mutated p53 and suggest perhaps a general mechanism for ATO-induced apoptosis.

Investigation of antioxidant enzymes in children with autistic disorder

Impaired antioxidant mechanisms are unable to inactivate free radicals that may induce a number of pathophysiological processes and result in cell injury. Thus, any abnormality in antioxidant defence systems could affect neurodevelopmental processes and could have an important role in the etiology of autistic disorder. The plasma levels of glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD), and erythrocyte levels of GSH-Px were investigated in 45 autistic children and compared with 41 normal controls. Levels of erythrocyte SOD, erythrocyte and plasma GSH-Px were assayed spectrophotometrically. Activities of erythrocyte SOD, erythrocyte and plasma GSH-Px in autistic children were significantly lower than normals. These results indicate that autistic children have low levels of activity of blood antioxidant enzyme systems; if similar abnormalities are present in brain, free radical accumulation could damage brain tissue.

Trace elements and antioxidant enzymes in Behçet's disease

Free oxygen radicals and insufficiency of antioxidant enzymes have been implicated in the pathogenesis of Behçet's disease (BD). Trace elements function as cofactors to antioxidant enzymes. The antioxidant system and trace elements were investigated in many different studies, including BD, but these subjects have not been investigated as a whole in these patients. The aim of the present study was to investigate the antioxidative system and trace elements in BD to contribute to the knowledge of pathogenesis and treatment of this disease. We examined glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activities together with selenium (Se), copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe) levels in plasma and erythrocytes of 50 patients with BD and 30 healthy controls. It was found that in patients with BD, erythrocyte GSH-Px and SOD activities and erythrocyte Se, plasma Fe, Mn, and Zn levels were significantly lower than those of controls and that plasma Cu, erythrocyte Zn, and Mn levels were significantly higher in patients with BD. Insufficient antioxidant enzyme activities were observed in patients with BD. The mechanism(s) of this phenomenon is not clear. Therefore, supplementation with trace elements involved in the antioxidative processes may increase scavenger enzyme activities, and consequently, an improvement in clinical symptoms may be expected.

pH-Metric log K calculations of famotidine, naproxen, nizatidine, ranitidine and salicylic acid

The octanol/water partition coefficient (log K) is one of the most commonly used parameters in structure-activity relationships in many areas such as drug design (including pesticides), pharmacokinetics, anesthesiology, environmental sciences, toxicology, bioaccumulation and predicting skin permeability as a predictive parameter. log K is generally determined using shake flask method, but the possibility of calculating log K using pH-metric titrations and half neutralization points is demonstrated in this study. The potentiometric pH titration technique has been developed as an automatic technique for log K determination but it can be achieved by manual titrations. This technique uses the pKa of the substance. The pKa of the substance shifts pK'a when the titration is repeated in the presence of octanol. log K value of the substance can be determined using pKa, pK'a values and relevant equation. The aim of the study was to determine the log K values of a series of compounds using pH-metric titrations and to compare pH-metric log K determination results with the other methods. The log K values of famotidine, naproxen, nizatidine, ranitidine and salicylic acid were determined using both shake flask method and potentiometric titrations. Their log K values were also calculated theoretically using computer program and all results were compared. The pH-metric log K values were found to be close to the shake flask method results. This method was found to be useful for the determination of log K values as it provides a high degree of accuracy even in the presence of titratable impurities in the solution.

Simultaneous determination of codeine and ethyl morphine HCL in tablet formulations using LC

A reverse phase high performance liquid chromatography (HPLC) method was developed for the simultaneous determination of codeine (methyl morphine) and dionin (ethyl morphine hydrochloride) in antitussive analgesic tablet formulations. A C(18) column and methanol-water (1:2) mixture mobile phase (pH 3.0) were used. Spectrophotometric detection was carried out at 210 nm. The total elution time was shorter than 7 min. This method was found to be quite precise and reproducible. This proposed method was successfully applied to the determination of codeine and ethyl morphine hydrochloride in tablets produced by the Turkish Army Drug Factory.

Simultaneous determination of acetaminophen, acetylsalicylic acid and ascorbic acid in tablet form using HPLC

The purpose of the present study was to develop a simple and accurate HPLC method to measure the amount of each agent in a multidrug pharmaceutical formulation. Three drugs, acetaminophen, acetylsalicylic acid and ascorbic acid, were analyzed simultaneously. A commercial pharmaceutical effervescent tablet was examined and the amount of each of these agents successfully determined. The present method appears to be more convenient than the current procedures described in American and British Pharmacopoeias in which each drug is assayed separately.

The effects of Azone and capsaicin on the permeation of naproxen through human skin

The permeation of naproxen through excised human skin and isolated perfused rabbit ear skin has been determined. It was found that both Azone and capsaicin enhanced the permeation with an enhancement ratio of up to 4-fold. The magnitudes of the effect were similar in human and rabbit skin. The permeation of naproxen from a saturated solution of the drug through skin pre-treated with Azone was similar to that from a commercial preparation (Naprosyn). In the perfused rabbit ear experiments the presence of capsaicin had no effect on the vasodilatation of the blood vessels, inferring that the penetration enhancement was a direct result of capsaicin influencing the barrier function of the skin. Structural similarities between Azone and capsaicin were seen using molecular graphics.