Antiplasmodial activity of the natural product compounds alstonine and himbeline.

Malaria, caused by Plasmodium parasites, continues to be a devastating global health issue. Despite a decline in malaria related deaths over the last decade, overall progress has plateaued. Key challenges to malaria prevention and control include the lack of a broadly effective vaccine and parasite drug resistance, including to the current gold standard artemisinin combination therapies (ACTs). New drugs with unique modes of action are therefore a priority for both the treatment and prevention of malaria. Unlike treatment drugs which need to kill parasites quickly to reduce or prevent clinical symptoms, compounds that kill parasites more slowly may be an option for malaria prevention. Natural products and natural product derived compounds have historically been an excellent source of antimalarial drugs, including the artemisinin component of ACTs. In this study, 424 natural product derived compounds were screened for in vitro activity against P. falciparum in assays designed to detect slow action activity, with 46 hit compounds identified as having >50% inhibition at 10 µM. Dose response assays revealed nine compounds with submicromolar activity, with slow action activity confirmed for two compounds, alstonine and himbeline (50% inhibitory concentration (IC50) 0.17 and 0.58 µM, respectively). Both compounds displayed >140-fold better activity against P. falciparum versus two human cell lines (Selectivity Index (SI) >1,111 and > 144, respectively). Importantly, P. falciparum multi-drug resistant lines showed no cross-resistance to alstonine or himbeline, with some resistant lines being more sensitive to these two compounds compared to the drug sensitive line. In addition, alstonine displayed cross-species activity against the zoonotic species, P. knowelsi (IC50 ~1 µM). Outcomes of this study provide a starting point for further investigations into these compounds as antiplasmodial drug candidates and the investigation of their molecular targets.

Malocclusion model of temporomandibular joint osteoarthritis in mice with and without receptor for advanced glycation end products.

OBJECTIVE: This study has two aims: 1. Validate a non-invasive malocclusion model of mouse temporomandibular joint (TMJ) osteoarthritis (OA) that we developed and 2. Confirm role of inflammation in TMJ OA by comparing the disease in the presence and absence of the receptor for advanced glycation end products (RAGE). DESIGN: The malocclusion procedure was performed on eight week old mice, either wild type (WT) or without RAGE. RESULTS: We observed TMJ OA at two weeks post-misalignment/malocclusion. The modified Mankin score used for the semi-quantitative assessment of OA showed an overall significantly higher score in mice with malocclusion compared to control mice at all times points (2, 4, 6 and 8 weeks). Mice with malocclusion showed a decrease in body weight by the first week after misalignment but returned to normal weight for their ages during the following weeks. The RAGE knock out (KO) mice had statistically lower modified Mankin scores compared to WT mice of the same age. The RAGE KO mice had statistically lower levels of Mmp-13 and HtrA1 but higher Tgf-ß1, as measured by immunohistochemistry, compared to WT mice at eight weeks post malocclusion. CONCLUSIONS: We demonstrate an inexpensive, efficient, highly reproducible and non-invasive model of mouse TMJ OA. The mechanical nature of the malocclusion resembles the natural development of TMJ OA in humans, making this an ideal model in future studies that aim to elucidate the pathogenesis of the disease leading to the discovery of a treatment. The RAGE plays a role in mouse TMJ OA.

Anomalous diffusion and memory effects on the impedance spectroscopy for finite-length situations.

The contribution of ions to the electrical impedance of an electrolytic cell limited by perfect blocking electrodes is determined by considering the role of the anomalous diffusion process and memory effects. Analytical solutions for fractional diffusion equations together with Poisson's equation relating the effective electric field to the net charge density are found. This procedure allows the construction of general expressions for the electrochemical impedance satisfying the Kramers-Kronig relations when the diffusion of ions in the cell is characterized by the usual, as well as by anomalous, behavior.

Direct laser writing of near-IR step-index buried channel waveguides in rare earth doped YAG.

A new (to our knowledge) ultrashort laser pulse irradiation regime that allows us to directly modify and increase the refractive index of rare earth doped YAG polycrystalline ceramics has been identified. Single-mode buried channel waveguides in both Ho:YAG and Er:YAG ceramics at the near-IR wavelengths of 1.55 µm and 1.95 µm are demonstrated by fabricating positive square step-index cores. Minimum propagation losses of 1.5 dB cm(-1) at a 1.51 µm wavelength have been preliminarily obtained. Confocal microluminescence mapping reveals that the increased refractive index regions retain the near-IR spectral properties of Er3+ ions in the YAG crystalline matrix.

Transmural differences in respiratory capacity across the rat left ventricle in health, aging, and streptozotocin-induced diabetes mellitus: evidence that mitochondrial dysfunction begins in the subepicardium.

In diabetic cardiomyopathy, ventricular dysfunction occurs in the absence of hypertension or atherosclerosis and is accompanied by altered myocardial substrate utilization and depressed mitochondrial respiration. It is not known if mitochondrial function differs across the left ventricular (LV) wall in diabetes. In the healthy heart, the inner subendocardial region demonstrates higher rates of blood flow, oxygen consumption, and ATP turnover compared with the outer subepicardial region, but published transmural respirometric measurements have not demonstrated differences. We aim to measure mitochondrial function in Wistar rat LV to determine the effects of age, streptozotocin-diabetes, and LV layer. High-resolution respirometry measured indexes of respiration in saponin-skinned fibers dissected from the LV subendocardium and subepicardium of 3-mo-old rats after 1 mo of streptozotocin-induced diabetes and 4-mo-old rats following 2 mo of diabetes. Heart rate and heartbeat duration were measured under isoflurane-anesthesia using a fetal-Doppler, and transmission electron microscopy was employed to observe ultrastructural differences. Heart rate decreased with age and diabetes, whereas heartbeat duration increased with diabetes. While there were no transmural respirational differences in young healthy rat hearts, both myocardial layers showed a respiratory depression with age (30-40%). In 1-mo diabetic rat hearts only subepicardial respiration was depressed, whereas after 2 mo diabetes, respiration in subendocardial and subepicardial layers was depressed and showed elevated leak (state 2) respiration. These data provide evidence that mitochondrial dysfunction is first detectable in the subepicardium of diabetic rat LV, whereas there are measureable changes in LV mitochondria after only 4 mo of aging.

Ultrafast laser inscription of near-infrared waveguides in polycrystalline ZnSe.

We report the successful fabrication of a low-loss near-IR waveguide in polycrystalline ZnSe using ultrafast laser inscription. The waveguide, which was inscribed using the multiscan fabrication technique, supported a well-confined mode at 1.55 µm. Propagation losses were characterized at 1.55 µm using the Fabry-Perot technique and found to be 1.07 dB · cm(-1) ± 0.03 dB · cm(-1).

Dispersive dielectric and conductive effects in 2D resistor-capacitor networks.

How to predict and better understand the effective properties of disordered material mixtures has been a long-standing problem in different research fields, especially in condensed matter physics. In order to address this subject and achieve a better understanding of the frequency-dependent properties of these systems, a large 2D L × L square structure of resistors and capacitors was used to calculate the immittance response of a network formed by random filling of binary conductor/insulator phases with 1000 Ω resistors and 10 nF capacitors. The effects of percolating clusters on the immittance response were studied statistically through the generation of 10 000 different random network samples at the percolation threshold. The scattering of the imaginary part of the immittance near the dc limit shows a clear separation between the responses of percolating and non-percolating samples, with the gap between their distributions dependent on both network size and applied frequency. These results could be used to monitor connectivity in composite materials. The effects of the content and structure of the percolating path on the nature of the observed dispersion were investigated, with special attention paid to the geometrical fractal concept of the backbone and its influence on the behavior of relaxation-time distributions. For three different resistor-capacitor proportions, the appropriateness of many fitting models was investigated for modeling and analyzing individual resistor-capacitor network dispersed frequency responses using complex-nonlinear-least-squares fitting. Several remarkable new features were identified, including a useful duality relationship and the need for composite fitting models rather than either a simple power law or a single Davidson-Cole one. Good fits of data for fully percolating random networks required two dispersive fitting models in parallel or series, with a cutoff at short times of the distribution of relaxation times of one of them. In addition, such fits surprisingly led to cutoff parameters, including a primitive relaxation or crossover time, with estimated values comparable to those found for real dispersive materials.

Origin of change in molecular-weight dependence for polymer surface tension.

Self-consistent-field theory is used to reproduce the behavior of polymer surface tension with molecular-weight for both lower and higher molecular-weight polymers. The change in behavior of the surface tension between these two regimes is shown to be due to the almost total exclusion of polymer from the nonpolymer bulk phase. The predicted two regime surface tension behavior with molecular-weight and the exclusion explanation are shown to be valid for a range of different polymer compressibilities.

Analysis of conducting-system frequency response data for an interfacial amorphous phase of copper-core oxide-shell nanocomposites.

Complex electrical-conductivity experimental data sets for the interfacial amorphous phase in copper-core-copper-oxide-shell nanostructured composites have been analyzed using two Kohlrausch-related frequency response models recently developed for analysis of the dispersive electrical response of conductive materials. Such analysis has been carried out for both the precursor (herein referred to as the reference) glass as well as the glass in which the core-shell nanostructure was developed after suitable heat treatment. Complex nonlinear-least-squares data fitting at each temperature employed composite Kohlrausch models that included electrode effects. Because of the lack of sufficient high-frequency data, it was necessary to use fixed, rather than free, values of the shape parameter beta1 of the model. On the basis of topological considerations, its values were set at 13 and 23 for the reference glass and the core-shell structured glass, respectively. The activation energies of resistivity for the reference and the treated glasses were found to have values of about 2 and 0.4 eV, respectively, indicating two different mechanisms of electrical conduction. A blocking-electrode measurement on the reference glass indicated the presence of an electronic as well as an ionic component of the electrical conductivity, with the ionic part dominating at the temperatures for which the present analyses were carried out.

Topological derivation of shape exponents for stretched exponential relaxation.

In homogeneous (ideal) glasses, the important dimensionless stretched-exponential shape parameter beta is described by magic (not adjusted) simple fractions derived from fractal configuration spaces of effective dimension d* determined by different topological axioms (rules) in the presence (absence) of a forcing electric field. The rules are based on a new central principle for defining glassy states: equal a priori distributions of fractal residual configurational entropy. Our approach and its beta estimates are fully supported by the results of relaxation measurements involving many different glassy materials and probe methods. The present unique topological predictions for beta typically agree with observed values to approximately 1% and indicate that for field-forced conditions beta should be constant for appreciable ranges of such exogenous variables as temperature and ionic concentration, as indeed observed using appropriate frequency-domain data analysis. The present approach can also be inverted and used to test sample homogeneity and quality.

Antitumor activity of irofulven against human ovarian cancer cell lines, human tumor colony-forming units, and xenografts.

The objective of this study was to investigate the cytotoxic activity of irofulven (HMAF, MGI 114), a unique chemotherapeutic agent currently under clinical investigation, in various preclinical models of ovarian cancer. Antiproliferative effects of irofulven in ovarian cancer cell lines and ovarian tumor specimens were characterized in vitro using sulforhodamine B and human tumor colony-forming assays, respectively. Irofulven demonstrated marked activity against a panel of ovarian tumor cell lines, including IGROV1, OVCAR-3, OVCAR-4, OVCAR-5, OVCAR-8, and SK-OV-3, all of which exhibit various drug resistance mechanisms. In human tumor cloning assays, irofulven inhibited colony formation in surgically derived ovarian tumors at concentrations as low as 0.001 micro g /ml and indicated superior activity in comparison with paclitaxel when tested against the same tumor specimens. The antitumor activity of irofulven compared to that of paclitaxel was also examined using the SK-OV-3 xenograft model. In mice bearing subcutaneously implanted SK-OV-3 tumors, treatment with paclitaxel failed to inhibit tumor growth; whereas mice treated with maximum tolerated doses of irofulven had a 25% partial shrinkage rate, and the remaining animals had a mean tumor growth inhibition of 82%. The potent activity of irofulven against ovarian tumors in vitro and in vivo supports the evaluation of its clinical activity in ovarian cancer.

Modafinil reduces excessive somnolence and enhances mood in patients with myotonic dystrophy.

OBJECTIVE: To evaluate the potential of modafinil in reducing excessive daytime somnolence (EDS) and enhancing indexes of quality of life and mood in patients with myotonic dystrophy (DM). METHODS: Forty patients with DM were randomized to receive modafinil and placebo for 14 days each, using a double-blind, cross-over design. Before and after each trial, subjects completed handgrip strength testing, spirometry, and quality-of-life measures (RAND). On days 7 and 14, each subject completed the Epworth Sleepiness Scale (ESS), the Stanford Sleepiness Scale (SSS), and the Profile of Mood States (POMS). RESULTS: ESS scores were lower while taking modafinil (mean 248 mm; 95% confidence limit 220 to 276 mm) as compared with placebo (309 mm; 281 to 336 mm) (p < 0.001). Mean SSS scores were also lower during the modafinil trial (3.05; 2.77 to 3.33) than during the placebo trial (3.45; 3.18 to 3.71) (p < 0.05). The POMS indicated that modafinil decreased fatigue-inertia (p < 0.001) and increased vigor-activity and tension-anxiety (p < 0.001) indexes. The total mood disturbance score was also decreased during the modafinil trial as compared with placebo (p < 0.05). The RAND quality-of-life measures of energy (p < 0.001) and health change (p < 0.05) were both significantly enhanced during the modafinil treatment phase. No changes in maximal grip strength or forced expired volume in 1 second were detected over the course of the study. Headache was the most frequently reported adverse event. Four patients withdrew from the study, three because of side effects (two during modafinil ingestion and one during placebo ingestion). CONCLUSION: Modafinil reduces somnolence and improves mood in patients with DM.

Potential causes, mechanisms, and implications of post exercise hypotension.

Post exercise hypotension (PEH) is a phenomenon of a prolonged decrease in resting blood pressure in the minutes and hours following acute exercise. Knowledge of PEH is potentially useful in designing first line strategies against hypertension as well as allowing a further understanding of blood pressure regulation in both health and disease. Following a brief review of blood pressure responses to exercise, this paper will provide a current and comprehensive summary of PEH and integrate the current state of knowledge surrounding it.

Post exercise hypotension is not mediated by the serotonergic system in borderline hypertensive individuals.

Recent evidence from our laboratory and others have suggested that the mechanism for a decrease in resting blood pressure after an acute bout of exercise is a centrally mediated decrease in total peripheral resistance. This study examined the effect of the central serotonergic system on post exercise hypotension (PEH) in 11 borderline hypertensive individuals (nine male, two female) aged 24.5 +/- 5.1 years. Each subject completed two, 30-min cycling bouts at 70% of VO2peak while under placebo or a selective serotonin re-uptake inhibitor (SSRI) treatment. Blood pressure was recorded directly from the radial artery, and treatments were randomised, double blinded and separated by at least 14 days. Baseline blood pressure was 145/72 mm Hg for systolic (SBP) and diastolic (DBP) respectively. Peripheral measures of serotonin (5-HT) were lower under SSRI treatment, whereas the major 5-HT metabolite, 5-hydroxyindoleacetic acid, was not significantly changed, indicating elevated central 5-HT levels. There was no difference in any of the haemodynamic variables between trials. Despite an increased heart rate for the initial 75 min post exercise, SBP was decreased as much as 23 mm Hg during the initial 60 min post exercise, after which it had returned to normal. DBP was unchanged after exercise. Circulating adrenaline (0.60 +/- 0.14 ng/mL to 1.3 +/- 1.6 ng/ml) and noradrenaline (0.27 +/- 0.31 ng/ml to 4.5 +/- 2.1 ng/ml) were significantly elevated during exercise. Both returned to pre-exercise levels within 15 min post exercise. Unexpectedly, oxygen uptake was slightly (5%), but significantly increased over the entire duration of the SSRI trial. We conclude that the central serotonergic system is not responsible for PEH in our borderline hypertensive population.

Structure-activity studies of antitumor agent irofulven (hydroxymethylacylfulvene) and analogues.

Many analogues of the antitumor agent irofulven have been readily prepared by replacing the allylic hydroxyl with a variety of nucleophiles. Analogues of acylfulvene (the precursor to irofulven) were also prepared by Michael reaction with acrolein. The toxicity of the analogues was determined, as well as preclinical antitumor activity. Several analogues exhibited good activity in mouse xenografts. Structural requirements for activity are discussed.

Toxicological assessment of gadoversetamide injection (OptiMARK), a new contrast-enhancement agent for use in magnetic resonance imaging.

RATIONALE AND OBJECTIVES: A series of preclinical tests were undertaken during the developmental process to determine the safety profile of gadoversetamide injection (OptiMARK). METHODS: Acute intravenous, acute intracisternal, and repeated-dose toxicities; cardiovascular effects; and genetic and reproductive toxicology characteristics were assessed in several animal species. RESULTS: Gadoversetamide injection demonstrated an acute intravenous median lethal dose of 25 to 28 mmol/kg and a maximum nonlethal dose of 14 mmol/kg in mice. In the dog, acute administration of gadoversetamide injection showed a no observable effect level at 3 mmol/kg. Dosed daily for 4 weeks, gadoversetamide injection (0.1 mmol x kg(-1) x d(-1)) caused no serious irreversible changes in any organs in rats and dogs. At a dose of 0.1 mmol/kg, gadoversetamide injection caused no significant (P < 0.05) changes in cardiovascular function in anesthetized dogs. Gadoversetamide injection showed no mutagenic activity. Fertility, reproductive performance, and postnatal fetal development were not affected at doses up to 0.5 mmol x kg(-1) x d(-1) in the rat. No teratogenicity was observed at doses up to 4.2 mmol x kg(-1) x d(-1) in the rat and up to 1.6 mmol x kg(-1) x d(-1) in the rabbit. CONCLUSIONS: Data from our toxicological assessment demonstrate the safety of gadoversetamide injection in a number of animal species at doses exceeding the intended human clinical dose.

Irofulven (6-hydroxymethylacylfulvene, MGI 114) induces caspase 8 and 9-mediated apoptosis in human pancreatic adenocarcinoma cells.

BACKGROUND: Irofulven (MGI 114) is a novel, clinically active sesquiterpene whose mechanism of action is not fully understood. We sought to identify apoptotic effectors induced by this agent in human pancreatic cancer cells. MATERIALS AND METHODS: MTT assay was used to assess IC50-Apoptosis was quantitated by flow cytometry and DAPI staining. Caspase activation was identified by western blot analysis. RESULTS: Irofulven was cytotoxic against all pancreatic cancer cell lines tested (IC50 1-18 microM), and induced 10-fold (4%+/- 2, vs. 41% +/- 5) induction of apoptosis. Irofulven-treated cells also demonstrated PARP3 cleavage and DAPI staining. Apoptosis was reduced to baseline levels by Z-VAD-FMK, a broad-spectrum caspase inhibitor. Western blot analysis revealed that caspases-3, -7, -8, and -9 were activated by irofulven. Time course evaluation demonstrated that caspases-8 and -9 were the initial species activated. CONCLUSION: Our data demonstrate that the cytotoxicity of irofulven in human pancreatic carcinoma cell lines is mediated by caspase-induced apoptosis.

Post exercise hypotension is sustained during subsequent bouts of mild exercise and simulated activities of daily living.

Our purpose was to examine whether the transient suppression of blood pressure that occurs during the hours following acute exercise (termed post exercise hypotension) persists throughout an active period of subsequent mild exercise and simulated activities of daily living (ADL) using direct measurements of arterial pressure. Eight recreationally active participants, with low borderline systolic hypertension completed 30 min of cycle ergometry at 70% VO(2Peak) and 30 min of quiet seated rest on separate days (randomised order). Following exercise and rest, subjects completed a 70-min protocol of mild exercise and simulated ADL. Blood pressure was monitored throughout by catheterisation of the radial artery. Exercise resulted in lower systolic (SBP), diastolic (DBP) and mean arterial pressure (MAP) throughout the post exercise ADL period compared to control measurements taken without prior exercise. The maximal difference in SBP, DBP and MAP between trials was 26, 7 and 13 mm Hg respectively. Average differences in SBP, DBP and MAP between trials were 16, 5 and 8 mm Hg respectively. This relative hypotension occurred in spite of higher heart rates during the ADL measurement period following the prior exercise. Furthermore, many of the blood pressure measurements during the post exercise period were significantly lower than the pre-exercise values during the same trial. We conclude that post exercise hypotension persists during mild exercise and simulated ADL. Although the duration of this relative hypotension needs to be determined, acute exercise may serve as a non-pharmacological aid in the treatment of hypertension.

In vivo antitumour efficacy of MGI-114 (6-hydroxymethylacylfulvene, HMAF) in various human tumour xenograft models including several lung and gastric tumours.

MGI-114 (6-hydroxymethylacylfulvene, HMAF) is a semi-synthetic analogue of the cytotoxic sesquiterpenoid illudins. In the present study, the in vivo antitumour efficacy of MGI-114 was examined in a panel of human tumour xenograft models consisting mainly of human lung and gastric tumours, and compared with that of other antitumour drugs such as irinotecan, paclitaxel, cisplatin, doxorubicin, vindesine, etoposide and 5-fluorouracil (5-FU). When different administration schedules were compared, daily administration of MGI-114 was found to be more effective than intermittent administrations. In human tumour xenograft models of nasopharyngeal, breast and colon carcinoma and melanoma, MGI-114 exerted a strong antitumour activity with complete tumour regression being observed. Moreover, in four human lung and three gastric tumour xenograft models, MGI-114 showed a strong antitumour activity with complete tumour regression being observed in some of the models. The antitumour efficacy of MGI-114 was generally higher than or equivalent to that of other antitumour drugs such as irinotecan and paclitaxel. These results support the potential utility of MGI-114 in the treatment of a variety of human solid tumours.

Short-term 17-beta-estradiol administration does not affect metabolism in young males.

We have previously demonstrated that females oxidize more lipid and less protein and carbohydrate during endurance exercise [21]. Several studies in male rats have demonstrated similar metabolic changes after 4 d of 17-beta-estradiol (E2) administration. Our purpose was to study the effects of E2 administration upon substrate metabolism during 90min of cycle ergometry at 60% VO2peak in 11 healthy, young males. E2 was administered in a single-blind, cross-over, randomized fashion for 11 d (100 microg.d(-1) x 3.5d --> 200 microg.d(-1) x 3.5 d --> 300 microg.d(-1) x 4.0 d). Respiratory exchange ratio (RER), VO2, Ve, HR, lactate, and glucose were measured every 30 min during exercise and E2, testosterone TEST, glycerol and triglycerides were measured prior to exercise T = 0 min. Muscle biopsies were taken from the vastus lateralis before and after exercise for glycogen determination. Estradiol treatment resulted in lower plasma TEST (20.8-->7.8 nmol.L(-1), P<0.0001) and higher plasma E2 (168.1 327.3 pmol.L(-1), P < 0.002). Therewere no effects of E2 treatment upon any of the other measured variables including muscle glycogen: (E2 - PRE = 529.3 --> POST = 237.9; PL-PRE = 582.2 --> POST = 262.4 mmol.kg(-1) [dm]). We concluded that short-term E2 treatment increased plasma E2 to female follicular levels in males but had no effect upon lipid or carbohydrate metabolism.