Kinetics of phloretin binding to phosphatidylcholine vesicle membranes.

The submillisecond kinetics for phloretin binding to unilamellar phosphatidylcholine (PC) vesicles was investigated using the temperature-jump technique. Spectrophotometric studies of the equilibrium binding performed at 328 nm demonstrated that phloretin binds to a single set of independent, equivalent sites on the vesicle with a dissociation constant of 8.0 microM and a lipid/site ratio of 4.0. The temperature of the phloretin-vesicle solution was jumped by 4 degrees C within 4 microseconds producing a monoexponential, concentration-dependent relaxation process with time constants in the 30--200-microseconds time range. An analysis of the concentration dependence of relaxation time constants at pH 7.30 and 24 degrees C yielded a binding rate constant of 2.7 X 10(8) M-1 s-1 and an unbinding constant of 2,900 s-1; approximately 66 percent of total binding sites are exposed at the outer vesicle surface. The value of the binding rate constant and three additional observations suggest that the binding kinetics are diffusion limited. The phloretin analogue, naringenin, which has a diffusion coefficient similar to phloretin yet a dissociation constant equal to 24 microM, bound to PC vesicle with the same rate constant as phloretin did. In addition, the phloretin-PC system was studied in buffers made one to six times more viscous than water by addition of sucrose or glycerol to the differ. The equilibrium affinity for phloretin binding to PC vesicles is independent of viscosity, yet the binding rate constant decreases with the expected dependence (kappa binding alpha 1/viscosity) for diffusion-limited processes. Thus, the binding rate constant is not altered by differences in binding affinity, yet depends upon the diffusion coefficient in buffer. Finally, studies of the pH dependence of the binding rate constant showed a dependence (kappa binding alpha [1 + 10pH-pK]) consistent with the diffusion-limited binding of a weak acid

Anion transport inhibitor binding to band 3 in red blood cell membranes.

The inhibitor of anion exchange 4,4'-dibenzoamido-2,2'-disulfonic stilbene (DBDS) binds to band 3, the anion transport protein in human red cell ghost membranes, and undergoes a large increase in fluorescence intensity when bound to band 3. Equilibrium binding studies performed in the absence of transportable anions show that DBDS binds to both a class of high-affinity (65 nM) and low-affinity (820 nM) sites with stoichiometry equivalent to 1.6 nmol/mg ghost protein for each site, which is consistent with one DBDS site on each band 3 monomer. The kinetics of DBDS binding were studied both by stopped-flow and temperature-jump experiments. The stopped-flow data indicate that DBDS binding to the apparent high-affinity site involves association with a low-affinity site (3 microM) followed by a slow (4 s-1) conformational change that locks the DBDS molecule in place. A detailed, quantitative fit of the temperature-jump data to several binding mechanisms supports a sequential-binding model, in which a first DBDS molecule binds to one monomer and induces a conformational change. A second DBDS molecule then binds to the second monomer. If the two monomers are assumed to be initially identical, thermodynamic characterization of the binding sites shows that the conformational change induces an interaction between the two monomers that modifies the characteristics of the second DBDS binding site

Effect of Aloe vera gel on some haematological parameters and serum electrolytes in high salt loaded Wistar rats

This study investigated the effect of Aloe vera gel on some haematological parameters and serum electrolytes in high salt loaded rats. Twenty (20) male Wistar rats (180-250 g) were randomly assigned into 4 groups (n=5): Control- received 0.2 ml normal saline; Aloe-received 600 mg/kg of Aloe vera gel orally once daily; Salt-fed (SF) received high salt diet (8% NaCl in feed + 1% NaCl in H2O); Saltfed-treated (SF+Aloe) received high salt diet + Aloe vera gel. All groups had access to rat feed and water throughout the duration (six weeks) of treatment. Blood samples were collected from each animal via cardiac puncture for analysis. Red blood cell (RBC) count, haemoglobin (Hb) concentration and packed cell volume (PCV) were significantly (p<0.05) increased in SF and SF+Aloe groups compared with control and Aloe groups. Total white blood cell count was significantly (p<0.001) decreased in SF group compared with control and Aloe groups and increased (p<0.001) in SF+Aloe group compared with SF group. Neutrophil and lymphocyte counts were significantly increased and decreased respectively in SF+Aloe group compared with control (p<0.01), Aloe (p<0.05) and SF (p<0.001) groups. Na+, K+ and Cl- concentrations were significantly increased in SF and SF+Aloe group compared with control and Aloe groups. HCO3- concentration was significantly increased in Aloe and SF+Aloe groups compared with control. High salt diet (HSD) caused alterations in red cell indices and posed threat to the immune system of rats. Aloe vera could not reverse these alterations but exhibited an immune-stimulatory effect. Both Aloe vera and HSD caused electrolyte imbalance. DOI: http://dx.doi.org/10.5281/zenodo.131828

A Temporal Threshold for Formaldehyde Crosslinking and Fixation

Formaldehyde crosslinking is in widespread use as a biological fixative for microscopy and molecular biology. An assumption behind its use is that most biologically meaningful interactions are preserved by crosslinking, but the minimum length of time required for an interaction to become fixed has not been determined.Using a unique series of mutations in the DNA binding protein MeCP2, we show that in vivo interactions lasting less than 5 seconds are invisible in the microscope after formaldehyde fixation, though they are obvious in live cells. The stark contrast between live cell and fixed cell images illustrates hitherto unsuspected limitations to the fixation process. We show that chromatin immunoprecipitation, a technique in widespread use that depends on formaldehyde crosslinking, also fails to capture these transient interactions.Our findings for the first time establish a minimum temporal limitation to crosslink chemistry that has implications for many fields of research

Etoricoxib in the treatment of osteoarthritis over 52-weeks: a double-blind, active-comparator controlled trial [NCT00242489]

BACKGROUND: The aim of this study was to evaluate the long-term efficacy and tolerability of etoricoxib, a COX-2 selective inhibitor, in osteoarthritis (OA) patients. METHODS: A double-blind, randomized, multicenter study was conducted in 617 patients with OA of the knee. The base study was 14 weeks in duration and consisted of 2 parts; in Part I (6 weeks), patients were allocated to once daily oral etoricoxib 5, 10, 30, 60, 90 mg or placebo. In Part II (8 weeks); the placebo, etoricoxib 5 and 10 mg groups were reallocated to etoricoxib 30, 60, or 90 mg qd or diclofenac 50 mg t.i.d. Treatment was continued for consecutive 12 and 26 week extensions. Primary efficacy endpoints were the WOMAC VA 3.0 pain subscale and investigator global assessment of disease status. Safety and tolerability were assessed by collecting adverse events throughout the study. RESULTS: Compared with placebo, the etoricoxib groups displayed significant (p < 0.05), dose-dependent efficacy for all primary endpoints in Part I; efficacy was maintained throughout the 52 weeks of the study. During the 46-week active-comparator controlled period, the etoricoxib groups demonstrated clinical efficacy that was similar to that of diclofenac 150 mg and was generally well tolerated, with a lower incidence of gastrointestinal (GI) nuisance symptoms compared with diclofenac (13.1, 14.7, and 13.5% for etoricoxib 30, 60, and 90 mg, respectively compared with 22.5% for diclofenac). CONCLUSION: In this extension study, etoricoxib, at doses ranging from 30 to 90 mg, demonstrated a maintenance of significant clinical efficacy in patients with OA through 52 weeks of treatment. Etoricoxib displayed clinical efficacy similar to diclofenac 150 mg and was generally well tolerated

The Whole Atmosphere Community Climate Model Version 6 (WACCM6)

The Whole Atmosphere Community Climate Model version 6 (WACCM6) is a major update of the whole atmosphere modeling capability in the Community Earth System Model (CESM), featuring enhanced physical, chemical and aerosol parameterizations. This work describes WACCM6 and some of the important features of the model. WACCM6 can reproduce many modes of variability and trends in the middle atmosphere, including the Quasi‐Biennial Oscillation, Stratospheric Sudden Warmings and the evolution of Southern Hemisphere springtime ozone depletion over the 20th century. WACCM6 can also reproduce the climate and temperature trends of the 20th century throughout the atmospheric column. The representation of the climate has improved in WACCM6, relative to WACCM4. In addition, there are improvements in high latitude climate variability at the surface and sea ice extent in WACCM6 over the lower top version of the model (CAM6) that come from the extended vertical domain and expanded aerosol chemistry in WACCM6, highlighting the importance of the stratosphere and tropospheric chemistry for high latitude climate variability

Family violence, war, and natural disasters: A study of the effect of extreme stress on children's mental health in Sri Lanka

Catani C, Jacob N, Schauer E, Kohila M, Neuner F. Family violence, war, and natural disasters: a study of the effect of extreme stress on children's mental health in Sri Lanka. BMC Psychiatry. 2008;8(1): 33.BACKGROUND: The consequences of war violence and natural disasters on the mental health of children as well as on family dynamics remain poorly understood. Aim of the present investigation was to establish the prevalence and predictors of traumatic stress related to war, family violence and the recent Tsunami experience in children living in a region affected by a long-lasting violent conflict. In addition, the study looked at whether higher levels of war violence would be related to higher levels of violence within the family and whether this would result in higher rates of psychological problems in the affected children. METHODS: 296 Tamil school children in Sri Lanka's North-Eastern provinces were randomly selected for the survey. Diagnostic interviews were carried out by extensively trained local Master level counselors. PTSD symptoms were established by means of a validated Tamil version of the UCLA PTSD Index. Additionally, participants completed a detailed checklist of event types related to organized and family violence. RESULTS: 82.4% of the children had experienced at least one war-related event. 95.6% reported at least one aversive experience out of the family violence spectrum. The consequences are reflected in a 30.4% PTSD and a 19.6% Major Depression prevalence. Linear regression analyses showed that fathers' alcohol intake and previous exposure to war were significantly linked to the amount of maltreatment reported by the child. A clear dose-effect relationship between exposure to various stressful experiences and PTSD was found in the examined children. CONCLUSION: Data argue for a relationship between war violence and violent behavior inflicted on children in their families. Both of these factors, together with the experience of the recent Tsunami, resulted as significant predictors of PTSD in children, thus highlighting the detrimental effect that the experience of cumulative stress can have on children's mental health

Study design and baseline characteristics of patients on dialysis in the ASCEND-D trial

BACKGROUND: The Anemia Studies in chronic kidney disease (CKD): Erythropoiesis via a Novel prolyl hydroxylase inhibitor (PHI) Daprodustat-Dialysis (ASCEND-D) trial will test the hypothesis that daprodustat is non-inferior to comparator epoetin alfa or darbepoetin alfa for two co-primary endpoints: haemoglobin efficacy and cardiovascular safety. METHODS: We report the trial design, key demographic, clinical, and laboratory findings, and baseline therapies of 2964 patients randomised in the open-label (sponsor-blinded) active-controlled, parallel-group, randomised ASCEND-D clinical trial. We also compare baseline characteristics of ASCEND-D patients with patients who are on dialysis (CKD G5D) enrolled in other large cardiovascular outcome trials (CVOTs) and in the most relevant registries. RESULTS: The median age of patients was 58 years, 43% were female; 67% were white and 16% were black. The median haemoglobin at baseline was 10.4 g/dL. Among randomised patients, 89% were receiving haemodialysis and 11% peritoneal dialysis. Among key co-morbidities, 42% reported a history of diabetes mellitus, and 45% a history of cardiovascular disease. Median blood pressure was 134/74 mmHg. The median weekly dose of epoetin was 5751 units. Intravenous and oral iron use was noted in 64% and 11% of patients, respectively. Baseline demographics were similar to patients with CKD G5D enrolled in other CVOTs and renal patient registries. CONCLUSION: ASCEND-D will evaluate the efficacy and safety of daprodustat compared with epoetin alfa or darbepoetin alfa in the treatment of patients with anaemia with CKD G5D

A preliminary randomized double blind placebo-controlled trial of intravenous immunoglobulin for Japanese encephalitis in Nepal

BACKGROUND: Japanese encephalitis (JE) virus (JEV) is a mosquito-borne flavivirus found across Asia that is closely related to West Nile virus. There is no known antiviral treatment for any flavivirus. Results from in vitro studies and animal models suggest intravenous immunoglobulin (IVIG) containing virus-specific neutralizing antibody may be effective in improving outcome in viral encephalitis. IVIG's anti-inflammatory properties may also be beneficial. METHODOLOGY/PRINCIPAL FINDINGS: We performed a pilot feasibility randomized double-blind placebo-controlled trial of IVIG containing anti-JEV neutralizing antibody (ImmunoRel, 400mg/kg/day for 5 days) in children with suspected JE at two sites in Nepal; we also examined the effect on serum neutralizing antibody titre and cytokine profiles. 22 children were recruited, 13 of whom had confirmed JE; 11 received IVIG and 11 placebo, with no protocol violations. One child (IVIG group) died during treatment and two (placebo) subsequently following hospital discharge. Overall, there was no difference in outcome between treatment groups at discharge or follow up. Passive transfer of anti-JEV antibody was seen in JEV negative children. JEV positive children treated with IVIG had JEV-specific neutralizing antibody titres approximately 16 times higher than those treated with placebo (p=0.2), which was more than could be explained by passive transfer alone. IL-4 and IL-6 were higher in the IVIG group. CONCLUSIONS/SIGNIFICANCE: A trial of IVIG for JE in Nepal is feasible. IVIG may augment the development of neutralizing antibodies in JEV positive patients. IVIG appears an appealing option for JE treatment that warrants further study. TRIAL REGISTRATION: ClinicalTrials.gov NCT01856205

Dermatitis associated with exposure to a marine cyanobacterium during recreational water exposure

<p>Abstract</p> <p>Background</p> <p>Anecdotal evidence reported an outbreak of symptoms on Fraser Island during the late 1990s similar to those expected from exposure to dermotoxins found in the cyanobacterium <it>L. majuscula</it>. This coincided with the presence of a bloom of <it>L. majuscula</it>.</p> <p>Methods</p> <p>Records from the Fraser Island National Parks First aid station were examined. Information on cyanobacterial blooms at Fraser Island were obtained from Queensland National Parks rangers.</p> <p>Results</p> <p>Examination of first aid records from Fraser Island revealed an outbreak of symptoms predominantly in January and February 1998.</p> <p>Conclusion</p> <p>During a bloom of <it>L. majuscula </it>there were numerous reports of symptoms that could be attributed to dermotoxins found in <it>L. majuscula</it>. The other four years examined had no <it>L. majuscula </it>blooms and the number of <it>L. majuscula </it>symptoms was much reduced. These cases comprised a high percentage of the cases treated at the first aid station.</p