Cell death in leukemia: passenger protein regulation by topoisomerase inhibitors

Etoposide is a potent inducer of mitotic catastrophe; a type of cell death resulting from aberrant mitosis. It is important in p53 negative cells where p53 dependent apoptosis and events at the G1 and G2 cell cycle checkpoints are compromised. Passenger proteins regulate many aspects of mitosis and siRNA interference or direct inhibition of Aurora B kinase results in mitotic catastrophe. However, there is little available data of clinical relevance in leukaemia models. Here, in p53 negative K562 myeloid leukemia cells, etoposide-induced mitotic catastrophe is shown to be time and/or concentration dependent. Survivin and Aurora remained bound to chromosomes. Survivin and Aurora were also associated with Cdk1 and were shown to form complexes, which in pull down experiments, included INCENP. There was no evidence of Aurora B kinase suppression. These data suggests etoposide will complement Aurora B kinase inhibitors currently in clinical trials for cancer.     

Endoplasmic reticulum stress and its regulator XBP-1 contributes to dendritic cell maturation and activation induced by high mobility group box-1 protein

High mobility group box-1 protein (HMGB1) had been proved to induce maturation and activation of dendritic cell (DC), however, the endogenous changes and mechanisms underlying are unknown. Since endoplasmic reticulum stress (ERS) activates an adaptive unfolded protein response (UPR) that facilitates cellular survival and repair, we hypothesized that HMGB1 may regulate the function of DC by modulating ERS. In our study, HMGB1 stimulation induced significant ERS responses in DCs in a time- and dose-dependent manner, demonstrated by the up-regulation of a number of ERS markers. Gene silence of XBP-1 in splenic DCs decreased the levels of CD80, CD86 as well as major histocompatibility complex (MHC)-II expression and cytokine secretion after HMGB1 treatment, when compared with untransfected or nontargeting-transfected DCs (all P<0.05). Moreover, XBP-1 silenced DCs after treatment with HMGB1 failed to stimulate notable proliferation and differentiation of T cells, unlike normal DCs or nontargeting-transfected DCs (all P<0.05). Gene silence of XBP-1 resulted in down-regulation of the receptor for advanced glycation end products (RAGE) expression on the surface of splenic DCs induced by HMGB1 stimulation (P<0.05). These findings demonstrate an important role for ERS and its regulator XBP-1 in HMGB1-induced maturation and activation of DCs.     

Effects of variations in intragastric volume on blood pressure and splanchnic blood flow during intraduodenal glucose infusion in healthy older subjects

The postprandial reduction in blood pressure (BP) is triggered by the interaction of nutrients with the small intestine and associated with an increase in splanchnic blood flow. Gastric distension may attenuate the postprandial fall in BP. The aim of this study was to determine the effects of differences in intragastric volume, including distension at a low (100 ml) volume, on BP and superior mesenteric artery (SMA) blood flow responses to intraduodenal glucose in healthy older subjects. BP and heart rate (HR; automated device), SMA blood flow (Doppler ultrasound), mesenteric vascular resistance (MVR), and plasma norepinephrine of nine male subjects (65-75 yr old) were measured after an overnight fast on 4 separate days in random order. On each day, subjects were intubated with a nasoduodenal catheter, incorporating a duodenal infusion port, and orally with a second catheter, incorporating a barostat bag, positioned in the fundus. Each subject received a 60-min (t = 0-60 min) intraduodenal glucose infusion (3 kcal/min) and gastric distension at a volume of 1) 0 ml (V0), 2) 100 ml (V100), 3) 300 ml (V300), or 4) 500 ml (V500). Systolic BP fell (P < 0.05) during V0, but not during V100, V300, or V500. In contrast, HR (P < 0.01) and SMA blood flow (P < 0.001) increased and MVR decreased (P < 0.05) comparably on all 4 days. Plasma norepinephrine rose (P < 0.01) in response to intraduodenal glucose, with no difference between the four treatments. There was a relationship between the areas under the curve for the change in systolic BP from baseline with intragastric volume (r = 0.60, P < 0.001). In conclusion, low-volume (≤100 ml) gastric distension has the capacity to abolish the fall in BP induced by intraduodenal glucose in healthy older subjects without affecting SMA blood flow or MVR. These observations support the concept that nonnutrient gastric distension prior to a meal has potential therapeutic applications in the management of postprandial hypotension.     

The design and synthesis of indazole and pyrazolopyridine based glucokinase activators for the treatment of Type 2 diabetes mellitus

Glucokinase activators represent a promising potential treatment for patients with Type 2 diabetes. Herein, we report the identification and optimization of a series of novel indazole and pyrazolopyridine based activators leading to the identification of 4-(6-(azetidine-1-carbonyl)-5-fluoropyridin-3-yloxy)-2-ethyl-N-(5-methylpyrazin-2-yl)-2H-indazole-6-carboxamide (42) as a potent activator with favorable preclinical pharmacokinetic properties and in vivo efficacy.     

Preferences and Self‐efficacy for Diet Modification Among Primary Care Patients

Limited data exist about patient preferences and self‐efficacy for different diets. We explored the preferences and self‐efficacy of primary care patients for reducing fat, reducing carbohydrates, or reducing calories. We conducted a self‐administered survey study of 71 primary care patients (response rate of 52%). Of patients, 59%, 53%, and 60% had high self‐efficacy for reducing fat, reducing carbohydrates, and reducing calories from their diet, respectively. Preferences were comparable, with 76% highly willing to reduce fat, 76% highly willing to reduce carbohydrates, and 72% of patients highly willing to reduce calories/portions. Female sex and higher BMI were associated with high self‐efficacy for all three dietary changes. A significantly higher proportion of nonwhites than whites had high self‐efficacy for reducing fat and reducing carbohydrates (P < 0.05). Obese patients in our study have similarly high willingness and self‐efficacy and comparable preferences for adopting changes consistent with three popular diets.     

Chemical composition and antidiabetic activity of Opuntia Milpa Alta extracts

Three new compounds, 1 – 3 , and 20 known compounds were isolated from the AcOEt and BuOH extract of edible Opuntia Milpa Alta. The petroleum ether extract was examined by GC and MS. A total of 26 compounds were identified, representing 95.6% of the total extract, phytosterol (36.03%) being the most abundant component, and polyunsaturated fatty acids (18.57%) represented the second largest group, followed by phytol (12.28%), palmitic acid, palmitate (13.54%), vitamin E (4.51%), and other compounds (7.47%). The effects of various extracts from edible Opuntia Milpa Alta (petroleum ether extract, AcOEt extract, BuOH extract, aqueous extract, H₂O parts) and the positive control (received dimethylbiguanide) were tested on streptozotocin (STZ)‐induced diabetic mice. The results indicated that all the treatment groups could significantly decrease blood glucose levels in STZ‐induced diabetic mice compared to the model control group (P<0.01), except the aqueous extract group (P<0.05). Especially, the petroleum ether extract group and the positive control group showed remarkable decrease of blood glucose levels. Taken together, the results indicate that the petroleum ether extract is the major hypoglycemic part in edible Opuntia Milpa Alta, which may be developed to a potential natural hypoglycemic functional ingredient.     

Effects of organic matter incorporation on nitrous oxide emissions from rice-wheat rotation ecosystems in China

Organic matter addition is thought to be an important regulator of nitrous oxide (N₂O) emissions from croplands. Contradictory effects, however, were reported in previous studies. To investigate the effects of crop residue management on N₂O emissions from rice-wheat rotation ecosystems, we conducted field experiments at three sites (Suzhou, Wuxi and Jiangdu) in the Yangtze River Delta, using static chamber and gas chromatography methods. Our data show that N₂O emissions throughout the rice season from plots treated with wheat straw application at a high rate (WS) prior to rice transplanting (1.1–2.0 kg N ha^?1) were significantly lower (P?<?0.05) than those from the control plots without organic matter addition or added with wheat straw at a moderate rate (1.6–2.9 kg N ha^?1). Furthermore, the WS treatments had a residual inhibitory effect on N₂O emissions in the following non-rice season, which consistently resulted in significantly lower emissions (P?<?0.05) compared to the control treatments (2.2–3.1 vs. 3.9–5.6 kg N ha^?1). In comparison to the control treatments, the WS treatments reduced both the seasonal and annual direct emission factors of the applied nitrogen (EF_d) by 50–68% (mean: 57%). The addition of compost (aerobically composted rice or wheat straw harvested in the last rotation) reduced the seasonal and annual EF_ds by 29–32%. Over the entire rice-wheat rotation cycle, annual N₂O emissions from the fertilized fields at the three sites ranged from 3.3?±?0.3 to 16.8?±?0.6 kg N ha^?1, with a coefficient of variation (CV) of 61%. Similarly, the EF_ds during the rice-wheat rotation cycle ranged from 0.4% to 2.5%, with a CV of 67%. These high spatial variations might have been related to: variations in soil properties, such as texture and soil organic carbon; management practices, such as straw treatments (i.e., compost versus fresh straw) and weather conditions, such as precipitation and rainfall distribution. Our results indicate that the incorporation of fresh wheat straw at a high rate during the rice season is an effective management practice for the mitigation of N₂O emissions in rice-wheat rotation systems. Whether this practice is also effective in reducing the overall global warming potential of net N₂O, CH₄ and CO₂ emissions needs to be seen through further studies.     

Assessing the trypanocidal potential of natural and semi-synthetic diketopiperazines from two deep water marine-derived fungi

Human African trypanosomiasis (HAT, commonly known as African sleeping sickness) is categorized as a neglected disease, as it afflicts >50,000 people annually in sub-saharan Africa, and there are few formal programs in the world focused on drug discovery approaches for this disease. In this study, we examined the crude extracts of two fungal strains (Aspergillus fumigatus and Nectria inventa) isolated from deep water sediment which provided >99% growth inhibition at 1 μg/mL of Trypanosoma brucei, the causative parasite of HAT. A collection of fifteen natural products was supplemented with six semi-synthetic derivatives and one commercially available compound. Twelve of the compounds, each containing a diketopiperazine core, showed excellent activity against T. brucei (IC₅₀ = 0.002–40 μM), with selectivity over mammalian cells as great as 20-fold. The trypanocidal diketopiperazines were also tested against two cysteine protease targets Rhodesain and TbCatB, where five compounds showed inhibition activity at concentrations less than 20 μM. A preliminary activity pattern is described and analyzed.