Effect of Metalaxyl on the incidence and severity of Pearl millet downy mildew disease in Northern Nigeria

Pearl millet downy mildew (DM) incidence, severity and yield losses of two pearl millet varieties (local and improved) due to the disease were determined in the field. Significant differences in the disease incidence and severity were recorded in the plots sown with metalaxyl-treated seeds and those sown with non-treated seeds, indicating the efficacy of the fungicide on the fungus. Yield losses due to non-treatment of seeds with metalaxyl was 40.88 and 45.39% in a local variety and 43.00 and 18.60% in an improved variety in the 2000 and 2001 cropping seasons respectively. Significant differences between plots sown with metalaxyl-treated and those sown with non-treated seeds were obtained for other yield components such as 1000-grains weight, panicle length and weight.     

Gene expression and the evolution of phenotypic diversity in social wasps

Background  

Organisms are capable of developing different phenotypes by altering the genes they express. This phenotypic plasticity provides a means for species to respond effectively to environmental conditions. One of the most dramatic examples of phenotypic plasticity occurs in the highly social hymenopteran insects (ants, social bees, and social wasps), where distinct castes and sexes all arise from the same genes. To elucidate how variation in patterns of gene expression affects phenotypic variation, we conducted a study to simultaneously address the influence of developmental stage, sex, and caste on patterns of gene expression in Vespula wasps. Furthermore, we compared the patterns found in this species to those found in other taxa in order to investigate how variation in gene expression leads to phenotypic evolution.     

Preservation of dried liposomes in the presence of sugar and phosphate

It has been well established that sugars can be used to stabilize liposomes during drying by a mechanism that involves the formation of a glassy state by the sugars as well as by a direct interaction between the sugar and the phospholipid head groups. We have investigated the protective effect of phosphate on solute retention and storage stability of egg phosphatidylcholine (egg PC) liposomes that were dried (air-dried and freeze-dried) in the presence of sugars and phosphate. The protective effect of phosphate was tested using both glucose (low T(g)) and sucrose (high T(g)) by measuring leakage of carboxyfluorescein (CF), which was incorporated inside the vesicles. Liposomes that were dried with glucose or phosphate alone showed complete leakage after rehydration. However, approximately 30% CF-retention was obtained using mixtures of phosphate and glucose. Approximately 75% CF-retention was observed with liposomes that were dried with sucrose. The solute retention further increased to 85% using mixtures of phosphate and sucrose. The pH of the phosphate buffer prior to drying was found to have a strong effect on the solute retention. Fourier transform infrared spectroscopy studies showed that phosphate and sugars form a strong hydrogen bonding network, which dramatically increased the T(g). The HPO(4)(2-) form of phosphate was found to interact stronger with sugars than the H(2)PO(4)(-) form. The increased solute retention of liposomes dried in the sugar phosphate mixtures did not coincide with improved storage stability. At temperatures below 60 degrees C the rate of solute-leakage was found to be strikingly higher in the presence of phosphate, indicating that phosphate impairs storage stability of dried liposomes.     

A randomised, blinded, placebo-controlled trial in dementia patients continuing or stopping neuroleptics (the DART-AD trial)

Background

There have been increasing concerns regarding the safety and efficacy of neuroleptics in people with dementia, but there are very few long-term trials to inform clinical practice. The aim of this study was to determine the impact of long-term treatment with neuroleptic agents upon global cognitive decline and neuropsychiatric symptoms in patients with Alzheimer disease.

Methods and Findings

Design: Randomised, blinded, placebo-controlled parallel two-group treatment discontinuation trial.Setting: Oxfordshire, Newcastle and Gateshead, London and Edinburgh, United Kingdom.Participants: Patients currently prescribed the neuroleptics thioridazine, chlorpromazine, haloperidol trifluoperazine or risperidone for behavioural or psychiatric disturbance in dementia for at least 3 mo.Interventions: Continue neuroleptic treatment for 12 mo or switch to an identical placebo.Outcome measures: Primary outcome was total Severe Impairment Battery (SIB) score. Neuropsychiatric symptoms were evaluated with the Neuropsychiatric Inventory (NPI).Results: 165 patients were randomised (83 to continue treatment and 82 to placebo, i.e., discontinue treatment), of whom 128 (78%) commenced treatment (64 continue/64 placebo). Of those, 26 were lost to follow-up (13 per arm), resulting in 51 patients per arm analysed for the primary outcome. There was no significant difference between the continue treatment and placebo groups in the estimated mean change in SIB scores between baseline and 6 mo; estimated mean difference in deterioration (favouring placebo) −0.4 (95% confidence interval [CI] −6.4 to 5.5), adjusted for baseline value (p = 0.9). For neuropsychiatric symptoms, there was no significant difference between the continue treatment and placebo groups (n = 56 and 53, respectively) in the estimated mean change in NPI scores between baseline and 6 mo; estimated mean difference in deterioration (favouring continue treatment) −2.4 (95% CI −8.2 to 3.5), adjusted for baseline value (p = 0.4). Both results became more pronounced at 12 mo. There was some evidence to suggest that those patients with initial NPI ≥ 15 benefited on neuropsychiatric symptoms from continuing treatment.

Conclusions

For most patients with AD, withdrawal of neuroleptics had no overall detrimental effect on functional and cognitive status. Neuroleptics may have some value in the maintenance treatment of more severe neuropsychiatric symptoms, but this benefit must be weighed against the side effects of therapy.Trial registration: Cochrane Central Registry of Controlled Trials/National Research Register (#ISRCTN33368770).     

Liposomes for cryopreservation of bovine sperm

In this study, the effect of various unilamellar liposomes on cryopreservation of bovine spermatozoa has been investigated. Liposomes were composed of saturated lipids with various acyl chain lengths: DSPC (18:0), DPPC (16:0), DMPC (14:0), or DLPC (12:0). Alternatively, liposomes were prepared using unsaturated egg phosphatidylcholine (EPC) or DOPC (18:1, neutral), alone or in combination with lipids with various head groups: DOPS (negatively charged), DOPG (negatively charged), and DOPE (neutral). Fourier transform infrared spectroscopy studies showed that bovine sperm membranes display a gradual phase transition from 10 to 24 ^oC. Phase transition temperatures of the liposomes varied from −20 to +53 ^oC. Sperm was incubated in the presence of liposomes for either 6 or 24 h at 4 °C prior to freezing. Postfreeze survival rates were determined based on the percentage of progressively motile cells as well as the percentage of acrosome- and plasma membrane-intact cells. With DOPC liposomes a postthaw progressive motility of 43% was obtained compared with 59% using standard egg yolk freezing extender. Postthaw progressive motility increased up to 52% using DOPC:DOPG (9:1) liposomes, whereas DOPC:DOPS or DOPC:DOPE liposomes did not increase survival compared with DOPC liposomes. Among the saturated lipids, only DMPC was found to increase cryosurvival, up to 44% based on progressive motility. DLPC liposomes caused a complete loss in cell viability, already prior to freezing, whereas DPPC and DSPC liposomes neither positively nor negatively affected cryosurvival. Taken together, the higher postthaw survival obtained with DOPC:DOPG liposomes as compared with DOPC liposomes can likely be attributed to increased liposome-sperm interactions between the charged phosphatidylglycerol groups and charged regions in the sperm membranes. Interestingly, the lipid phase state of the liposomes during preincubation is not the decisive factor for their cryoprotective action.     

Optimal concentrations of cryoprotective agents for semen from stallions that are classified 'good' or 'poor' for freezing

Cryopreserved stallion sperm displays a high degree of male-to-male variability with respect to cell viability after thawing. Animals that have semen with low viability after cryopreservation are classified as 'poor' freezers, and when post-thaw viability is high they are designated as 'good' freezers. Cryoprotective agents that are used for cryopreserving stallion sperm include glycerol, ethylene glycol, methyl formamide, and dimethylformamide, and are typically used in concentrations ranging from 1% to 4%. The aim of this study was to evaluate the osmotic stresses that stallion sperm is exposed to during cryopreservation, and to determine if sperm from 'good' and 'poor' freezers show differences in osmotic tolerance limits and in the suitability of cryoprotective agents. Concentrations of 2-3% of the above mentioned cryoprotectants with freezing extender osmolalities ranging from 580 to 895 mOsm kg(-1) showed the highest motility rates after freeze-thaw, both for 'good' and 'poor' freezers, for all cryoprotectants tested with slightly higher values for glycerol. Freeze-thawed semen from 'poor' freezers was found to have a lower percentage of progressively motile sperm compared to that of 'good' freezers. Assessment of plasma and acrosomal membrane integrity after return to isosmotic conditions revealed that cryopreserved sperm from 'poor' freezers showed lower osmotic tolerance limits as compared to sperm from 'good' freezers. Semen from 'poor' freezers that was frozen using freezing extenders supplemented with more then 2% cryoprotectant showed decreased viability and increased acrosome reaction upon return to isoosmotic conditions, whereas 'good' freezers could withstand cryoprotectant concentrations up to 3% before a decline in viability was observed.     

Myometrial apoptosis: activation of the caspase cascade in the pregnant rat myometrium at midgestation

In the present study, we determined the contribution of myometrial hyperplasia, hypertrophy, and apoptosis to uterine growth during pregnancy. The changes in two endogenous markers of cell replication, proliferating cell nuclear antigen (PCNA) protein expression and bromodeoxyuridine (BrdU) incorporation, were studied. Myocyte hypertrophy was assessed by measuring the protein:DNA ratio. The expression levels of antiapoptotic regulatory proteins (BCL2 and BCL2L1) and enzymes involved in apoptosis (caspases 3, 6, 7, 9, and 10) were assessed by immunoblotting throughout gestation and postpartum. Myometrial cell apoptosis was determined by TUNEL staining and DNA fragmentation assays. Both BrdU incorporation and PCNA labeling were elevated in early pregnant myometrium and decreased dramatically after midgestation, with a simultaneous increase in cellular hypertrophy. Levels of BCL2 were high during early gestation, followed by significantly elevated levels of BCL2L1 at midgestation. The expression of caspase 10 in myometrial samples declined from a high nonpregnant level to a complete loss at early gestation. The cleaved forms of caspases (CC) 3, 6, 7, and 9, as well as poly(ADP-ribose)polymerase-1, were undetectable in the myometrial samples at early or late gestation but were transiently elevated at midgestation. Immunohistochemical staining of CC3 confirmed the activation of the caspase cascade, but TUNEL-positive staining or the increase in DNA fragmentation was not detected. Collectively, two distinct phases of myometrial growth were observed: myocyte hyperplasia associated with an increase in antiapoptotic proteins during the first half of gestation, and cellular hypertrophy during the second part of gestation. The transition between these phases was associated with transient activation of the caspase cascade that triggered the differentiation of uterine smooth muscle.     

Ice premelting during differential scanning calorimetry

Premelting at the surface of ice crystals is caused by factors such as temperature, radius of curvature, and solute composition. When polycrystalline ice samples are warmed from well below the equilibrium melting point, surface melting may begin at temperatures as low as -15 degrees C. However, it has been reported (. Biophys. J. 65:1853-1865) that when polycrystalline ice was warmed in a differential scanning calorimetry (DSC) pan, melting began at about -50 degrees C, this extreme behavior being attributed to short-range forces. We show that there is no driving force for such premelting, and that for pure water samples in DSC pans curvature effects will cause premelting typically at just a few degrees below the equilibrium melting point. We also show that the rate of warming affects the slope of the DSC baseline and that this might be incorrectly interpreted as an endotherm. The work has consequences for DSC operators who use water as a standard in systems where subfreezing runs are important.