Drug-resistant breast carcinoma (MCF-7) cells are paradoxically sensitive to apoptosis

The purpose of this study was to determine whether expression of tissue transglutaminase (TG2) and caspase-3 proteins in drug-resistant breast carcinoma MCF-7/DOX cells would render these cells selectively susceptible to apoptotic stimuli. Despite high resistance to multidrug resistance (MDR)-related drug, doxorubicin (> or =150-fold), the MCF-7/DOX cells were extremely sensitive to apoptotic stimuli. Thus, calcium ionophore, A23187 (A23187) and the protein kinase C inhibitor staurosporine (STS) each induced rapid and time-dependent apoptosis in MCF-7/DOX cells. The apoptosis induced by either agent was accompanied by caspase-3 activation and other downstream changes that are typical of cells undergoing apoptosis. The alterations upstream of caspase-3 activation, however, such as loss in mitochondrial membrane potential (DeltaPsi), release of cytochrome c, and activation of caspase-8, and caspase-9, were detected only in STS-treated cells. The A12387 failed to induce any of the caspase-3 upstream changes, implying that A23187-induced apoptosis may utilize one or more novel upstream pathways leading to the activation of caspase 3. In summary, these data demonstrate that MCF-7/DOX cells are much more sensitive to apoptotic stimuli than previously thought and that A23187-induced apoptosis may involve some novel, yet unidentified, upstream pathway that leads to the activation of caspase-3 and other downstream events.     

Estimating optimal profiles of genetic alterations using constraint-based models

Metabolic engineering involves application of recombinant DNA methods to manipulate metabolic networks to improve cellular properties. It is critical that the genetic alterations be performed in an optimal manner to maximize profit. In addition to the product yield, productivity consideration is also critical, especially for the production of bulk chemicals such as 1,3-propanediol. In this work, we demonstrate that it is suboptimal from the standpoint of productivity to induce genetic alteration at the start of the production process. A bi-level optimization scheme is formulated to determine the optimal temporal flux profile for the manipulated reaction. In the first case study, an optimal flux in the reaction catalyzed by glycerol kinase is determined to maximize the glycerol production at the end of a 6-h batch cultivation of Escherichia coli under aerobic conditions. The final glycerol concentration is 30% higher for the optimal flux profile compared with having an active flux during the entire batch. The effect of the mass transfer coefficient on the optimal profile and the glycerol concentration is also determined. In the second case study, the anaerobic batch fermentation of the ldh(-) strain of Escherichia coli is considered. The optimal flux in the acetate pathway is determined to maximize the final ethanol concentration. The optimal flux results in higher ethanol concentration (11.92 mmol L(-1)) compared to strains with no acetate flux (8.36 mmol L(-1)) and fully active acetate flux (6.22 mmol L(-1)). We also examine the effects of growth inhibition due to high ethanol concentrations and variations in final batch time on ethanol production.     

Prevalence of Undiagnosed Depression among Persons with Hypertension and Associated Risk Factors: A Cross-Sectional Study in Urban Nepal

BackgroundDespite an increasing number of studies exploring prevalence of depression among hypertensive patients in high income countries, limited data is available from low and middle income countries, particularly Nepal. Our aim was to investigate the prevalence of undiagnosed (sub clinical) depression and associated risk factors among hypertensive patients attending a tertiary health care clinic in Nepal.MethodsThe study was based on a cross-sectional study design, with 321 hypertensive patients attending the Out-Patient Department of a central hospital in Nepal. Blood measure was recorded via a mercury column sphygmomanometer. Depression levels were assessed using the Beck Depression Inventory-Ia (BDI) scale. Demographics and risk factors were assessed.ResultThe proportion of participants with undiagnosed depression was 15%. Multivariable analyses demonstrated an increase in BDI scores with increased aging. Approximately a 1 point increase in the BDI score was observed for each additional decade of aging in hypertensive patients. Additional factors associated with increased risk of depression included being female (4.28 point BDI score increase), smoking (5.61 point BDI score increase), being hypertensive with no hypertensive medication (4.46 point BDI score increase) and being illiterate (4.46 point BDI score increase).ConclusionsAmong persons with hypertension in outpatient settings in Nepal, demographic (age, sex, education), behavioural (smoking,) and adherence factors (anti-hypertensive medication) were associated with undiagnosed depression. Screening programs in Nepal may assist early intervention in hypertensive patients with sub clinical depression.     

Structure Based In Silico Analysis of Quinolone Resistance in Clinical Isolates of Salmonella Typhi from India

Enteric fever is a major cause of morbidity in several parts of the Indian subcontinent. The treatment for typhoid fever majorly includes the fluoroquinolone group of antibiotics. Excessive and indiscriminate use of these antibiotics has led to development of acquired resistance in the causative organism Salmonella Typhi. The resistance towards fluoroquinolones is associated with mutations in the target gene of DNA Gyrase. We have estimated the Minimum Inhibitory Concentration (MIC) of commonly used fluoroquinolone representatives from three generations, ciprofloxacin, ofloxacin, levofloxacin and moxifloxacin, for 100 clinical isolates of Salmonella Typhi from patients in the Indian subcontinent. The MICs have been found to be in the range of 0.032 to 8 μg/ml. The gene encoding DNA Gyrase was subsequently sequenced and point mutations were observed in DNA Gyrase in the quinolone resistance determining region comprising Ser83Phe/Tyr and Asp87Tyr/Gly. The binding ability of these four fluoroquinolones in the quinolone binding pocket of wild type as well as mutant DNA Gyrase was computationally analyzed by molecular docking to assess their differential binding behaviour. This study has revealed that mutations in DNA Gyrase alter the characteristics of the binding pocket resulting in the loss of crucial molecular interactions and consequently decrease the binding affinity of fluoroquinolones with the target protein. The present study assists in understanding the underlying molecular and structural mechanism for decreased fluoroquinolone susceptibility in clinical isolates as a consequence of mutations in DNA Gyrase.     

PAX6 Regulates Melanogenesis in the Retinal Pigmented Epithelium through Feed-Forward Regulatory Interactions with MITF

During organogenesis, PAX6 is required for establishment of various progenitor subtypes within the central nervous system, eye and pancreas. PAX6 expression is maintained in a variety of cell types within each organ, although its role in each lineage and how it acquires cell-specific activity remain elusive. Herein, we aimed to determine the roles and the hierarchical organization of the PAX6-dependent gene regulatory network during the differentiation of the retinal pigmented epithelium (RPE). Somatic mutagenesis of Pax6 in the differentiating RPE revealed that PAX6 functions in a feed-forward regulatory loop with MITF during onset of melanogenesis. PAX6 both controls the expression of an RPE isoform of Mitf and synergizes with MITF to activate expression of genes involved in pigment biogenesis. This study exemplifies how one kernel gene pivotal in organ formation accomplishes a lineage-specific role during terminal differentiation of a single lineage.     

Electronic structure and stabilities of Ni-doped germanium nanoclusters: a density functional modeling study

The present study reports the geometry, electronic structure, growth behavior and stability of neutral and ionized nickel encapsulated germanium clusters containing 1–20 germanium atoms within the framework of a linear combination of atomic orbital density functional theory (DFT) under a spin polarized generalized gradient approximation. In the growth pattern, Ni-capped Ge_n and Ni-encapsulated Ge_n clusters appear mostly as theoretical ground state at a particular size. To explain the relative stability of the ground state clusters, variation of different parameters, such as average binding energy per atom (BE), embedding energy (EE) and fragmentation energy (FE) of the clusters, were studied together with the size of the cluster. To explain the chemical stability of the clusters, different parameters, e.g., energy gap between the highest occupied and lowest unoccupied molecular orbitals (HOMO–LUMO gap), ionization energy (IP), electron affinity (EA), chemical potential (μ), chemical hardness (η), and polarizability etc. were calculated and are discussed. Finally, natural bond orbital (NBO) analysis was applied to understand the electron counting rule applied in the most stable Ge₁₀Ni cluster. The importance of the calculated results in the design of Ge-based superatoms is discussed.