Assessment of pulmonary toxicity of MgO nanoparticles in rats

In this study, we have evaluated the pulmonary toxicity of MgO nanoparticles (MgO NPs) in rats following their exposure. NPs in phosphate buffered saline + 1% Tween 80 were exposed via intratracheal instillation at a doses of 1 mg/kg or 5 mg/kg into rat lungs and evaluated for various tissue damage markers like alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) in bronchoalveolar lavage (BAL) fluid and histopathology of lungs at 1, 7, and 30 days of post‐exposure intervals. A dose‐dependant increase in ALP and LDH activity was observed in BAL fluids of rat lungs than sham control at all post‐exposure periods (P <0.05), and a dose‐dependant infiltration of interstitial lymphocytes, peribronchiolar lymphocytic infiltration, and dilated and/or congested vessels at 1 day post‐exposure period, worsened at 1 week period, and were reduced at 1 month at histology, indicating the pulmonary toxicity of MgO NPs. In conclusion, MgO NPs exposure produced a dose‐dependent pulmonary toxicity in rats and was comparable with that of Quartz particles. © 2013 Wiley Periodicals, Inc. Environ Toxicol 30: 308–314, 2015.     

A non-ATP-competitive inhibitor of BCR-ABL overrides imatinib resistance

Imatinib, which is an inhibitor of the BCR-ABL tyrosine kinase, has been a remarkable success for the treatment of Philadelphia chromosome-positive (Ph+) chronic myelogenous leukemias (CMLs). However, a significant proportion of patients chronically treated with imatinib develop resistance because of the acquisition of mutations in the kinase domain of BCR-ABL. Mutations occur at residues directly implicated in imatinib binding or, more commonly, at residues important for the ability of the kinase to adopt the specific closed (inactive) conformation to which imatinib binds. In our quest to develop new BCR-ABL inhibitors, we chose to target regions outside the ATP-binding site of this enzyme because these compounds offer the potential to be unaffected by mutations that make CML cells resistant to imatinib. Here we describe the activity of one compound, ON012380, that can specifically inhibit BCR-ABL and induce cell death of Ph+ CML cells at a concentration of <10 nM. Kinetic studies demonstrate that this compound is not ATP-competitive but is substrate-competitive and works synergistically with imatinib in wild-type BCR-ABL inhibition. More importantly, ON012380 was found to induce apoptosis of all of the known imatinib-resistant mutants at concentrations of <10 nM concentration in vitro and cause regression of leukemias induced by i.v. injection of 32Dcl3 cells expressing the imatinib-resistant BCR-ABL isoform T315I. Daily i.v. dosing for up to 3 weeks with a >100 mg/kg concentration of this agent is well tolerated in rodents, without any hematotoxicity.     

Enhanced production and dendritic growth of new dentate granule cells in the middle-aged hippocampus following intracerebroventricular FGF-2 infusions

Declined production and diminished dendritic growth of new dentate granule cells in the middle-aged and aged hippocampus are correlated with diminished concentration of fibroblast growth factor-2 (FGF-2). This study examined whether increased FGF-2 concentration in the milieu boosts both production and dendritic growth of new dentate granule cells in the middle-aged hippocampus. The FGF-2 or vehicle was infused into the posterior lateral ventricle of middle-aged Fischer (F)344 rats for 2 weeks using osmotic minipumps. New cells born during the first 12 days of infusions were labeled via daily intraperitoneal injections of 5'-bromodeoxyuridine (BrdU) and analysed at 10 days after the last BrdU injection. Measurement of BrdU(+) cells revealed a considerably enhanced number of new cells in the subgranular zone (SGZ) and granule cell layer (GCL) of the dentate gyrus (DG) ipsilateral to FGF-2 infusions. Characterization of beta-III tubulin(+) neurons among newly born cells suggested an increased addition of new neurons to the SGZ/GCL ipsilateral to FGF-2 infusions. Quantification of DG neurogenesis at 8 days post-infusions via doublecortin (DCX) immunostaining also revealed the presence of an enhanced DG neurogenesis ipsilateral to FGF-2 infusions. Furthermore, DCX(+) neurons in FGF-2-infused rats exhibited enhanced dendritic growth compared with their counterparts in vehicle-infused rats. Thus, subchronic infusion of FGF-2 is efficacious for stimulating an enhanced DG neurogenesis from neural stem/progenitor cells in the middle-aged hippocampus. As dentate neurogenesis is important for hippocampal-dependent learning and memory and DG long-term potentiation, strategies that maintain increased FGF-2 concentration during ageing may be beneficial for thwarting some of the age-related cognitive impairments.     

Strategies for promoting anti-seizure effects of hippocampal fetal cells grafted into the hippocampus of rats exhibiting chronic temporal lobe epilepsy

Efficacy of hippocampal fetal cell (HFC) grafting for restraining spontaneous recurrent motor seizures (SRMS) in chronic temporal lobe epilepsy (TLE) is unknown. We investigated both survival and anti-seizure effects of 5'-bromodeoxyuridine (BrdU) labeled embryonic day 19 (E19) HFC grafts pretreated with different neurotrophic factors and a caspase inhibitor. Grafts were placed bilaterally into the hippocampi of F344 rats exhibiting kainate (KA) induced chronic TLE, where the frequency of SRMS varied from 3.0 to 3.5 seizures/8-h duration. The first group received standard (untreated) HFC grafts, the second group received HFC grafts pretreated and transplanted with brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3) and caspase inhibitor Ac-YVAD-cmk (BNC-treated HFC grafts), the third group received HFC grafts pretreated and transplanted with fibroblast growth factor-2 (FGF-2) and caspase inhibitor Ac-YVAD-cmk (FC-treated HFC grafts), and the fourth group served as epilepsy-only controls. Epileptic rats receiving standard HFC grafts exhibited 119% increase in the frequency of SRMS at 2 months post-grafting consistent with 125% increase in seizure frequency observed in epilepsy-only controls during the same period. However, in epileptic rats receiving HFC grafts treated with BNC or FC, the frequency of SRMS was 33-39% less than their pre-transplant scores and 73-76% less than rats receiving standard HFC grafts or epilepsy-only rats. The yield of surviving neurons was equivalent to 30% of injected cells in standard HFC grafts, 57% in HFC grafts treated with BNC and 98% in HFC grafts treated with FC. Thus, standard HFC grafts survive poorly in the chronically epileptic hippocampus and fail to restrain the progression of chronic TLE. In contrast, HFCs treated and grafted with BNC or FC survive robustly in the chronically epileptic hippocampus, considerably reduce the frequency of SRMS and blunt the progression of chronic TLE.     

Hypoglycemia in inpatients after gatifloxacin or levofloxacin therapy: nested case-control study

STUDY OBJECTIVES: To compare the incidence of hypoglycemic events in patients exposed to gatifloxacin or levofloxacin, and to measure the odds of experiencing a hypoglycemic event after receiving gatifloxacin versus levofloxacin while adjusting for confounders. DESIGN: Nested case-control study within a historical cohort. SETTING: A tertiary care, 730-bed, teaching hospital in central Illinois. PATIENTS: Seven thousand two hundred eighty-seven hospitalized patients who received gatifloxacin or levofloxacin therapy. MEASUREMENTS AND MAIN RESULTS: A total of 113 patients (case patients) had blood glucose levels below 51 mg/dl; 113 control patients, matched for age and sex, had no hypoglycemia. Matched conditional logistic regression models adjusted the odds of having hypoglycemia for significant covariates. The 12-month incidence of hypoglycemia was 11/1000 patients after levofloxacin administration and 21/1000 patients after gatifloxacin (absolute risk increase 10/1000 patients, 95% confidence interval [CI] 4-16/1000). Renal failure, sepsis syndrome, and concomitant hypoglycemic drug therapy significantly predicted hypoglycemia. After adjustment for significant predictors, the odds of having hypoglycemia were 2.81 (95% CI 1.02-7.70) times higher after gatifloxacin than levofloxacin therapy. CONCLUSION: Among inpatients, the incidence of hypoglycemic events is greater after treatment with gatifloxacin than levofloxacin. The odds of experiencing hypoglycemic events are greater with gatifloxacin even after adjusting for other hypoglycemia risk factors, such as concomitant hypoglycemic drugs, renal failure, and sepsis syndrome.     

‘Where did the tube go?’ A case of retropharyngeal submucosal false passage during nasal intubation

Nasotracheal intubation could be associated with a variety of complications, of which traumatic complications are commonly encountered. We present a rare case of retropharyngeal submucosal false passage which occurred during nasotracheal intubation inspite of avoiding potential risk factors known for causing nasopharyngeal trauma. Risk factors, preventive measures and probable reason for this complication have been discussed.     

In vivo selection for metastasis promoting genes in the mouse

Here, we report the identification of a metastasis promoting factor by a forward genetic screen in mice. A retroviral cDNA library was introduced into the nonmetastatic cancer cell line 168FARN, which was then orthotopically transplanted into mouse mammary fat pads, followed by selection for cells that metastasize to the lung. The genes encoding the disulfide isomerase ERp5 and beta-catenin were found to promote breast cancer invasion and metastasis. Disulfide isomerases (thiol isomerases), which catalyze disulfide bond formation, reduction, and isomerization, have not previously been implicated in cancer cell signaling and tumor metastasis. Overexpression of ERp5 promotes both in vitro migration and invasion and in vivo metastasis of breast cancer cells. These effects were shown to involve activation of ErbB2 and phosphoinositide 3-kinase (PI3K) pathways through dimerization of ErbB2. Activation of ErbB2 and PI3K subsequently stimulates RhoA and beta-catenin, which mediate the migration and invasion of tumor cells. Inhibition of ErbB2 and PI3K reverses the phenotypes induced by ERp5. Finally, ERp5 was shown to be up-regulated in human surgical samples of invasive breast cancers. These data identify a link between disulfide isomerases and tumor development, and provide a mechanism that modulates ErbB2 and PI3K signaling in the promotion of cancer progression.     

Deletion of kasB in Mycobacterium tuberculosis causes loss of acid-fastness and subclinical latent tuberculosis in immunocompetent mice

Mycobacterium tuberculosis, the causative agent of tuberculosis, has two distinguishing characteristics: its ability to stain acid-fast and its ability to cause long-term latent infections in humans. Although this distinctive staining characteristic has often been attributed to its lipid-rich cell wall, the specific dye-retaining components were not known. Here we report that targeted deletion of kasB, one of two M. tuberculosis genes encoding distinct beta-ketoacyl- acyl carrier protein synthases involved in mycolic acid synthesis, results in loss of acid-fast staining. Biochemical and structural analyses revealed that the DeltakasB mutant strain synthesized mycolates with shorter chain lengths. An additional and unexpected outcome of kasB deletion was the loss of ketomycolic acid trans-cyclopropanation and a drastic reduction in methoxymycolic acid trans-cyclopropanation, activities usually associated with the trans-cyclopropane synthase CmaA2. Although deletion of kasB also markedly altered the colony morphology and abolished classic serpentine growth (cording), the most profound effect of kasB deletion was the ability of the mutant strain to persist in infected immunocompetent mice for up to 600 days without causing disease or mortality. This long-term persistence of DeltakasB represents a model for studying latent M. tuberculosis infections and suggests that this attenuated strain may represent a valuable vaccine candidate against tuberculosis.     

Anti-proliferative effects of 20-epi-vitamin-D3 analogue,KH1060 in human neuroblastoma: induction of RAR-beta and p21(Cip1)

We determined the in vitro biological activities of 1 alpha, 25-dihdroxyvitamin D(3) (1,25-D(3)) and its analogue, 20-epi-22-oxa-24a, 26a, 27a-trihomo-1 alpha, 25 (OH)(2) vitamin D(3) (KH1060) in six human neuroblastoma (NB) cell lines (SH-SY5Y, NB69, SK-N-AS, IMR5, CHP-134, NGP). The ability of these compounds to inhibit cell growth and DNA synthesis was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and BrdU incorporation, respectively. The induction of cell death was monitored by caspase-3 activity. Their antineoplastic effect was assessed by clonal proliferation in soft agar. KH1060 was more effective than 1,25 D(3) in inhibiting cell growth and DNA synthesis. The IC-(50) (inhibition of 50% cell viability) indicated that KH1060 was about 10-20-fold more potent than 1,25 D(3). This growth inhibition was also accompanied by induction of caspase-3 activity, indicating that these compounds induce cell death in a caspase-dependent fashion. Moreover, KH1060 exerted potent antineoplastic activity by suppressing the clonal proliferation of the six NB cells. For the first time we demonstrate that KH1060 induces the expression of retinoic acid receptor-beta and p21(Cip1) suggesting that these proteins in part mediate the growth inhibitory effects. Taken together, all the six NB cells were more susceptible to growth inhibition by KH1060 than 1,25-D(3), suggesting its possible use in NB to potentiate the action of retinoids, which are in clinical use for this disease.