Tackling breast cancer chemoresistance with nano-formulated siRNA.

Breast cancer is the leading cancer diagnosed in women and the second leading cause of cancer-related deaths in women. Current limitations to standard chemotherapy in the clinic are extensively researched, including problems arising from repeated treatments with the same drugs. The phenomenon that cancer cells become resistant toward certain chemo drugs is called chemotherapy resistance. In this review, we are focusing on nanoformulation of siRNA for the fight against breast cancer chemoresistance.

Lift vs. drag based mechanisms for vertical force production in the smallest flying insects.

We used computational fluid dynamics to determine whether lift- or drag-based mechanisms generate the most vertical force in the flight of the smallest insects. These insects fly at Re on the order of 4-60 where viscous effects are significant. Detailed quantitative data on the wing kinematics of the smallest insects is not available, and as a result both drag- and lift-based strategies have been suggested as the mechanisms by which these insects stay aloft. We used the immersed boundary method to solve the fully-coupled fluid-structure interaction problem of a flexible wing immersed in a two-dimensional viscous fluid to compare three idealized hovering kinematics: a drag-based stroke in the vertical plane, a lift-based stroke in the horizontal plane, and a hybrid stroke on a tilted plane. Our results suggest that at higher Re, a lift-based strategy produces more vertical force than a drag-based strategy. At the Re pertinent to small insect hovering, however, there is little difference in performance between the two strategies. A drag-based mechanism of flight could produce more vertical force than a lift-based mechanism for insects at Re<5; however, we are unaware of active fliers at this scale.

No effect of short-term exposure to high-fibre diets on the gastrointestinal morphology of layer hens (Gallus gallus domesticus): body reserves are used to manage energy deficits in favour of phenotypic plasticity.

Using layer hens, Gallus gallus domesticus, we compared the digestive capabilities of birds on a low-fibre diet (LF, 8.49% neutral detergent fibre; NDF), with those fed a high-fibre diet balanced for energy and protein to match the LF diet (high fibre balanced, HFB; NDF = 15.61%) and those fed a high fibre unbalanced (HFU) diet (NDF = 16.68%). The HFU diet had the lowest apparent dry matter (DM) metabolisability at 58.14 ± 6.46%, followed by HFB, 65.87 ± 3.50 and the LF diet, 70.49 ± 7.07%. Despite significant differences between apparent DM metabolisabilities of LF and HFU diets, no morphometric changes in the gastrointestinal tract (GIT) of layer hens were observed (including crop, gizzard, proventriculus, liver, large intestine, paired caeca and small intestine). Conversely, body mass losses were recorded for animals on HFU diet, while those on the LF and HFB diets actually gained body mass over the 14-day trials. We suggest that the body mass losses seen in the animals fed HFU diets were attributed to losses in adipose tissue, but this was not quantified. Assuming body mass losses were mainly in adipose tissue, we propose that adipose may act to buffer environmental challenges like shortfalls in nutrient acquisition when dietary energy requirements are not met. Compared with smaller birds (e.g. quail), the larger body size of the layer hens may offer them a greater safety margin in terms of body energy reserves before changes in the GIT might be needed to redress energy deficits associated with hard-to-digest, high-fibre diets.

Oxidative decarboxylation of free and peptide-linked amino acids in phagocytizing guinea pig granulocytes.

The oxidative decarboxylation of amino acids by a system consisting of myeloperoxidase-hydrogen peroxide-chloride has been demonstrated previously by others and the process has been considered to be part of the microbicidal armamentarium of some phagocytic leukocytes. We were able to translate these earlier observations, made on model systems, to intact guinea pig granulocytes. We could demonstrate differences in the cellular handling of peptide-linked amino acids as particles, compared with free amino acids. Specific inhibitors were used to explore two routes of oxidative decarboxylation: (a) the myeloperoxidase-catalyzed direct decarboxylation-deamination reaction, and (b) oxidation of alpha-keto acids after transamination of amino acids. These inhibitors were cyanide, azide, and tapazole for the former pathway, and amino-oxyacetate for the latter. Amino-oxyacetate profoundly inhibited the decarboxylation of free 14C-amino acids (alanine and aspartate) in both resting and stimulated cells, but had only a minimal effect on 14CO2 production from ingested insoluble 14C-protein. On the other hand, the peroxidase inhibitors cyanide, azide, and tapazole dramatically inhibited the production of 14CO2 from ingested particulate 14C-protein, but had only small effects on the decarboxylation of free amino acid. Soluble, uniformly labeled 14C-protein was not significantly converted to 14CO2 even in the presence of phagocytizable polystyrene beads. These observation suggest that the amino acids taken up by phagocytosis (e.g., as denatured protein particles) are oxidatively decarboxylated and deaminated in the phagosomes by the myeloperoxidase-hydrogen peroxide-chloride system; soluble free amino acids that enter the cytoplasm by diffusion or transport are oxidatively decarboxylated after transamination by the normal cellular amino acid oxidative pathway.

Modelling heating of liver tumours with heterogeneous magnetic microsphere deposition.

Ferromagnetic embolization hyperthermia (FEH) is a novel treatment for liver cancer. Magnetic microspheres are injected into the hepatic artery and cluster in the periphery of tumours and are heated with externally applied magnetic fields. In order to more accurately simulate FEH, we modelled a three-dimensional heterogeneous distribution of heat sources. We constructed a fractal model of the vasculature in the periphery of a tumour. We used this model to compute the spatial distribution of the microspheres that lodge in capillaries. We used the distribution model as input to a finite-element heat transfer model of the FEH treatment. The overall appearance of the vascular tree is subjectively similar to that of the disorganized vascular network which encapsulates tumours. The microspheres are distributed in the tumour periphery in similar patterns to experimental observations. We expect the vasculature and microsphere deposition models to also be of interest to researchers of any targeted cancer therapies such as localized intra-arterial chemotherapy and selective internal radiotherapy. Our results show that heterogeneous microsphere distributions give significantly different results to those for a homogeneous model and thus are preferable when accurate results are required.

Increased collagen-linked fluorescence in skin of young patients with type I diabetes mellitus.

Our objective was to determine whether the fluorescence of skin collagen, which may reflect the accumulation of advanced glycosylation end products, is increased in young patients with type I (insulin-dependent) diabetes. Our study design was a cross-sectional case-control study in a referral-based diabetic clinic in an academic hospital. Study subjects comprised a convenience sample of 18 type I diabetic patients aged 17-30 yr and 8 age-matched healthy control subjects. The fluorescence of collagen was measured in skin biopsy material. Collagen-linked fluorescence (CLF) was increased in diabetic patients (mean 10.5 [range 5.8-15.8] U/mg) compared with control subjects (7.6 [5.6-10.1] U/mg, P less than 0.02). In diabetic patients, CLF was related to age (r = 0.581) and duration of diabetes (r = 0.697) but not concentration of glycosylated hemoglobin (r = 0.082). Partial correlation analysis demonstrated that duration of diabetes is the main factor determining the fluorescence of collagen in these patients. There was a relationship between CLF and presence of diabetic retinopathy after the data were adjusted for patient age and duration of diabetes (P = 0.023). Increased fluorescence of skin collagen can be detected in young type I diabetic patients and is primarily related to duration of diabetes.

Simulation of nitrous oxide emissions at field scale using the SPACSYS model.

Nitrous oxide emitted to the atmosphere via the soil processes of nitrification and denitrification plays an important role in the greenhouse gas balance of the atmosphere and is involved in the destruction of stratospheric ozone. These processes are controlled by biological, physical and chemical factors such as growth and activity of microbes, nitrogen availability, soil temperature and water availability. A comprehensive understanding of these processes embodied in an appropriate model can help develop agricultural mitigation strategies to reduce greenhouse gas emissions, and help with estimating emissions at landscape and regional scales. A detailed module to describe the denitrification and nitrification processes and nitrogenous gas emissions was incorporated into the SPACSYS model to replace an earlier module that used a simplified first-order equation to estimate denitrification and was unable to distinguish the emissions of individual nitrogenous gases. A dataset derived from a Scottish grassland experiment in silage production was used to validate soil moisture in the top 10 cm soil, cut biomass, nitrogen offtake and N2O emissions. The comparison between the simulated and observed data suggested that the new module can provide a good representation of these processes and improve prediction of N2O emissions. The model provides an opportunity to estimate gaseous N emissions under a wide range of management scenarios in agriculture, and synthesises our understanding of the interaction and regulation of the processes.

Occurrence and impact of negative behaviour, including domestic violence and abuse, in men attending UK primary care health clinics: a cross-sectional survey.

OBJECTIVE: To measure the experience and perpetration of negative behaviour, including domestic violence and abuse (DVA), and investigate its associations with health conditions and behaviours in men attending general practice. DESIGN: Cross-sectional questionnaire-based study conducted between September 2010 and June 2011. SETTING: 16 general practices in the south west of England. PARTICIPANTS: Male patients aged 18 or older, attending alone, who could read and write English. A total of 1403 of eligible patients (58%) participated in the survey and 1368 (56%) completed the questions relevant to this paper. 97% of respondents reported they were heterosexual. MAIN OUTCOME MEASURES: Lifetime occurrence of negative behaviour consistent with DVA, perceived health impact of negative behaviours, associations with anxiety and depression symptoms, and cannabis use in the past 12 months and binge drinking. RESULTS: 22.7% (95% CI 20.2% to 24.9%) of men reported ever experiencing negative behaviour (feeling frightened, physically hurt, forced sex, ask permission) from a partner. All negative behaviours were associated with a twofold to threefold increased odds of anxiety and depression symptoms in men experiencing or perpetrating negative behaviours or both. 34.9% (95% CI 28.7% to 41.7%) of men who reported experiencing negative behaviour from a partner, and 30.8% (95% CI 23.7% to 37.8%) of men who perpetrated negative behaviours said they had been in a domestically violent or abusive relationship. No associations with problematic drinking were found; there was a weak association with cannabis use. CONCLUSIONS: DVA is experienced or perpetrated by a large minority of men presenting to general practice, and these men were more likely to have current symptoms of depression and anxiety. Presentation of anxiety or depression to clinicians may be an indicator of male experience or perpetration of DVA victimisation.

Pentamidine congeners. 2. 2-butene-bridged aromatic diamidines and diimidazolines as potential anti-Pneumocystis carinii pneumonia agents.

We have synthesized cis and trans geometric isomers 1-8 as semirigid congeners of pentamidine. Compounds 1-4 were more potent than pentamidine in treating Pneumocystis carinii pneumonia in immunosuppressed rats. These compounds also demonstrated no clinical toxicity or histopathologic abnormalities. Introduction of methoxy substituents meta to the amidine or imidazoline groups of the phenyl rings as in compounds 5-8 generally resulted in compounds with decreased anti-P. carinii activity and increased toxicity to the host. Compounds 1-4 were evaluated as DNA binders. These compounds showed greater affinity for poly(dA).poly(dT) than for calf thymus DNA. The cis isomers, 1 and 2, demonstrated greater affinity for DNA than their trans counterparts 3 and 4. This difference in DNA binding affinity, however, did not reflect in a corresponding difference in the anti-P. carinii activity of these compounds.

Analogues of 1,5-bis(4-amidinophenoxy)pentane (pentamidine) in the treatment of experimental Pneumocystis carinii pneumonia.

A series of 33 analogues of the anti-Pneumocystis carinii drug 1,5-bis(4-amidinophenoxy)pentane (pentamidine) was synthesized for screening against a rat model of P. carinii pneumonia (PCP). Twenty-five of the compounds showed efficacy against PCP when compared to a saline-treated control group. Two compounds, 1,4-bis(4-amidinophenoxy)butane (butamidine, 6) and 1,3-bis(4-amidino-2-methoxyphenoxy)propane (DAMP, 16), were statistically more effective than the parent drug in treating PCP in the rat model of infection. In addition to their activity against PCP, the compounds were also evaluated for antitrypsin activity, ability to inhibit thymidylate synthetase, affinity for DNA, and toxicity. No correlation was observed between the tested molecular interactions of the diamidines and their effectiveness against PCP.

Dicationic diarylfurans as anti-Pneumocystis carinii agents.

Seven dicationic 2,5-diarylfurans have been synthesized, and their interactions with poly(dA-dT) and the duplex oligomer d(CGCCAATTCGCG)2 were evaluated by Tm measurements. The inhibition of topoisomerase II isolated from Giardia lamblia, the inhibition of growth of G. lamblia in cell culture by these furans, and the effectiveness of these compounds against Pneumocystis carinii in the immunosuppressed rat model have been assessed. Strong binding affinities to poly(dA-dT) and to the oligomer were observed for the dicationic furans, and the interaction strength is directly correlated to the biological activity of the compounds. An X-ray structure for the complex of the dicationic amidine derivative, 2,5-bis(4-guanylphenyl)furan (1), with the oligomer demonstrates the snug fit of these compounds with the AATT minor-groove binding site and hydrogen bonds to AT base pairs at the floor of the minor groove. The stronger DNA binding molecules are the most effective inhibitors of topoisomerase II and G. lamblia in cell culture, and there is a correlation for both DNA interaction and topoisomerase II inhibition with the biological activity of these compounds against G. lamblia. Compound 1 is the most effective against P. carinii, it is more active and less toxic than pentamidine on intravenous administration and it is also effective by oral dosage. The results presented here suggest a model for the biological action of these compounds in which the dication first binds in the minor groove of DNA and forms a complex that results in the inhibition of the microbial topoisomerase II enzyme.

Methotrexate pharmacokinetics in psoriatic patients developing hepatic fibrosis.

Methotrexate sodium is a well-established therapeutic agent for severe psoriasis, but its use may be associated with hepatic fibrosis. We studied the pharmacokinetics of oral and intramuscular methotrexate in two groups of patients--those who did and those who did not develop hepatic fibrosis while receiving methotrexate therapy. Our results showed no difference between the two groups for peak or 24-hour methotrexate concentrations; for area under the curve to 24, 144, and 24 to 144 hours; or in total-body methotrexate clearance. Measurement of methotrexate plasma levels after drug administration is therefore unlikely to help in identifying those patients at risk of developing fibrosis.

Paradoxical sleep and depth perception.

It has been hypothesised that one possible function of paradoxical (REM) sleep is the maintenance of facilitation of co-ordinated eye movements. A prediction from this hypothesis is that binocular depth perception will be more accurate at the end of periods of paradoxical sleep than at the beginning. The results from previous studies are conflicting. Using two groups of eight healthy male volunteers in a two factor repeated measures design, it was found that for a period of paradoxical sleep in the second half of the night only, there was an improvement in binocular depth perception accuracy between the beginning and end of paradoxical sleep. The accuracy at the end of the paradoxical sleep was not significantly different to that on going to bed or on awakening in the morning; the effect was due to a large decrease in accuracy at the start of the REM period. There was no effect of paradoxical sleep on binocular depth perception in the early part of the night. Monocular depth perception accuracy was unaffected by paradoxical sleep.

Experimental examination of a targeted hyperthermia system using inductively heated ferromagnetic microspheres in rabbit kidney.

It is known that significant heating can be generated by magnetic hysteresis effects in small ferromagnetic particles exposed to a rapidly alternating magnetic field. If such particles can be made to infiltrate the vascular bed surrounding a tumour by intravascular infusion then it may be possible to generate sufficient heating to destroy the tumour by hyperthermia. One of the constraints on such a technique is the limited amount of magnetic material that can be delivered to a tumour via the intravascular route and the consequent heating that can be induced by this material. Here, we report on a series of experiments in which doses of microspheres containing different amounts of ferromagnetic material were infused into rabbit kidneys via the renal artery with the aim of testing whether adequate tissue heating could be achieved using realistic concentrations of the embolised material. Heating rates were measured for each infused quantity under similar conditions with the animal alive and dead to examine the role of blood flow in the heating process. The results show that tissue temperatures above the therapeutic threshold of 42 degrees C can be readily achieved using this method with clinically relevant concentrations of microspheres in living tissue.

A magnetic resonance imaging based method for measurement of tissue iron concentration in liver arterially embolized with ferrimagnetic particles designed for magnetic hyperthermia treatment of tumors.

Rabbit liver was loaded with ferrimagnetic particles of gamma -Fe2 O3 (designed for magnetic hyperthermia treatment of liver tumors) by injecting various doses of a suspension of the particles into the hepatic artery in vivo. Proton transverse relaxation rate (R(2)) images of the livers in vivo, excised, and dissected were generated from a series of single spin-echo images. Mean R(2) values for samples of ferrimagnetic-particle-loaded liver dissected into approximate 1 cm cubes were found to linearly correlate with tissue iron concentration over the range from approximately 0.1 to at least 2.7 mg Fe/g dry tissue when measured at room temperature. Changing the temperature of ferrimagnetic-particle-loaded samples of liver from 1 degrees C to 37 degrees C had no observable effect on tissue R(2) values. However, a small but significant decrease in R(2) was found for control samples containing no ferrimagnetic material on raising the temperature from 1 degrees C to 37 degrees C. Both chemically measured iron concentrations and mean R(2) values for rabbit livers with implanted tumors tended to be higher than those measured for tumor-free liver. This study indicates that tissue R(2) measurement and imaging by nuclear magnetic resonance may have a useful role in magnetic hyperthermia therapy protocols for the treatment of liver cancer.

Detection of DNA damage and repair by alkaline elution using human lymphocytes.

The repair of DNA alkylation damage in human cells is poorly understood. We have adapted the alkaline elution technique for use with human peripheral blood lymphocytes in culture. We have also established conditions necessary for short-term culture of human lymphocytes. Lymphocyte growth which can be maintained for up to 30 days is dependent upon irradiated TK6 feeder cells and T-cell growth factor (crude TCGF). The amount of damage induced by a given concentration of methyl methane-sulfonate (MMS) is dependent upon cell number per ml of growth medium. The DNA damage measured, in lymphocytes, by alkaline elution is a composite of single strand breaks and alkali-labile lesions. Repair of this damage after appropriate recovery periods is also detectable. The irradiated feeder TK6 cells do not contribute to the number of strand breaks detected or the amount of recovery after treatment. This method offers a quick and reproducible means of detecting DNA damage and repair in human T-lymphocytes.

Decreased DNA repair in familial Alzheimer's disease.

Alterations in the capacity of a cell to repair DNA lesions play an important role in a number of human diseases. We and others have demonstrated defective DNA repair of alkylation damage in cells from patients with Alzheimer's disease. It has been hypothesized that this defect is related to the cause of Alzheimer's disease and results in the accumulation of lesions in the central nervous system neurons. One prediction of this hypothesis is that in dominantly inherited Alzheimer's disease, the repair defect will be present in half of the offspring of affected patients long before they develop symptoms of the disease. In order to test the hypothesis that decreased DNA repair is responsible for familial Alzheimer's disease and their at-risk offspring we have studied DNA repair in these individuals after exposure of lymphoblasts to alkylating agents. Our results indicate that cell lines from affected patients repair significantly less damage in 3 h than cell lines from healthy controls. A small number of at-risk individuals were also studied and some of these had lower levels of repair, although more cell lines from individuals in this group must be studied. These findings provide further support for defective DNA repair playing a role in the pathogenesis of Alzheimer's disease.

A randomised clinical trial of nicotine patches for treatment of spit tobacco addiction among adolescents.

BACKGROUND: This study tested the efficacy of nicotine patches in combination with behavioural therapy for the treatment of adolescent spit tobacco addiction. Prior interventions had resulted in mean cessation rates below 15% at one year. METHODS: This study, the PATCH Project, used a three group, placebo controlled, randomised clinical trial design. The control group received a standard 3-5 minute counselling followed by a two week follow up phone call. The two intervention groups received a six week behavioural intervention; in addition, one group received active nicotine patches while the other group received placebo patches. Both groups received quarterly stage based telephone counselling. RESULTS: At one year, the usual care group's spit tobacco cessation rate was 11.4% (exact 95% confidence interval (CI) 6.1% to 19.1%), placebo patch 25.0% (95% CI 16.9% to 34.7%), and the active patch 17.3% (95% CI 10.4% to 26.3%). When both patch groups were combined, the cessation rate was 21.2% (95% CI 15.7% to 27.6%). The cessation rates for active and placebo patch were not significantly different (exact two sided p = 0.22), while the combined patch groups had a significantly greater cessation rate than usual care (exact two sided p = 0.04). CONCLUSIONS: The behavioural intervention proved to be about twice as successful as previous interventions, but the nicotine patch offered no improvement in cessation rates. The behavioural intervention is based on publicly available materials and can be easily adapted for widespread use, particularly in high schools.

Incidence of Blastocystis hominis in faecal samples submitted for routine microbiological analysis.

Over a one-year period, 1390 faecal samples were submitted to Aberystwyth Public Health Laboratory for routine microbiological examination. All were stained using a commercial trichrome method. Blastocystis hominis was detected in 96 (6.9%), making it the most common parasite found in the study. Of the B. hominis-positive specimens, 73% were missed on direct microscopy. Molecular typing of B. hominis has revealed extensive genetic diversity in morphologically identical strains and thus detection by microscopy alone may not be sufficient to confirm the role of this organism in human disease.

Detection of Dientamoeba fragilis by culture.

Symptoms associated with Dientamoeba fragilis include diarrhoea, abdominal pain, nausea, vomiting, epigastric pain and weight loss. A possible link between D. fragilis and irritable bowel syndrome (IBS)-like symptoms has been reported, and therefore the presence of this parasite should be excluded before making a diagnosis of IBS. Over a six-month period, 976 faecal samples were submitted to NPHS Microbiology Aberystwyth for routine microbiological analysis. All samples were also cultured for parasites using Robinson's xenic medium. Trichrome staining was undertaken whenever practicable, but many stools had insufficient material. D. fragilis was isolated from 25 (2.6%) patients, whereas Cryptosporidium spp. was detected in 16 (1.6%) patients. D. fragilis was only detected in nine (1.3%) out of 685 specimens stained with trichrome, although four of the 25 culture-positive stools had insufficient sample for staining. Parasite culture proved to be less laborious than trichrome staining and dramatically increased D. fragilis detection rate.