A covalently bound photoisomerizable agonist. Comparison with reversibly bound agonists at electrophorus electroplaques

After disulphide bonds are reduced with dithiothreitol, trans-3- (α-bromomethyl)-3’-[α- (trimethylammonium)methyl]azobenzene (trans-QBr) alkylates a sulfhydryl group on receptors. The membrane conductance induced by this “tethered agonist” shares many properties with that induced by reversible agonists. Equilibrium conductance increases as the membrane potential is made more negative; the voltage sensitivity resembles that seen with 50 [mu]M carbachol. Voltage- jump relaxations follow an exponential time-course; the rate constants are about twice as large as those seen with 50 μM carbachol and have the same voltage and temperature sensitivity. With reversible agonists, the rate of channel opening increases with the frequency of agonist-receptor collisions: with tethered trans-Qbr, this rate depends only on intramolecular events. In comparison to the conductance induced by reversible agonists, the QBr-induced conductance is at least 10-fold less sensitive to competitive blockade by tubocurarine and roughly as sensitive to “open-channel blockade” bu QX-222. Light-flash experiments with tethered QBr resemble those with the reversible photoisomerizable agonist, 3,3’,bis-[α-(trimethylammonium)methyl]azobenzene (Bis-Q): the conductance is increased by cis {arrow} trans photoisomerizations and decreased by trans {arrow} cis photoisomerizations. As with Bis-Q, ligh-flash relaxations have the same rate constant as voltage-jump relaxations. Receptors with tethered trans isomer. By comparing the agonist-induced conductance with the cis/tans ratio, we conclude that each channel’s activation is determined by the configuration of a single tethered QBr molecule. The QBr-induced conductance shows slow decreases (time constant, several hundred milliseconds), which can be partially reversed by flashes. The similarities suggest that the same rate-limiting step governs the opening and closing of channels for both reversible and tethered agonists. Therefore, this step is probably not the initial encounter between agonist and receptor molecules.     

Genome-wide differentially methylated genes in prostate cancer tissues from African-American and Caucasian men

Increasing evidence suggests that aberrant DNA methylation changes may contribute to prostate cancer (PCa) ethnic disparity. To comprehensively identify DNA methylation alterations in PCa disparity, we used the Illumina 450K methylation platform to interrogate the methylation status of 485,577 CpG sites focusing on gene-associated regions of the human genome. Genomic DNA from African-American (AA; 7 normal and 3 cancers) and Caucasian (Cau; 8 normal and 3 cancers) was used in the analysis. Hierarchical clustering analysis identified probe-sets unique to AA and Cau samples, as well as common to both. We selected 25 promoter-associated novel CpG sites most differentially methylated by race (fold change > 1.5-fold; adjusted P < 0.05) and compared the β-value of these sites provided by the Illumina, Inc. array with quantitative methylation obtained by pyrosequencing in 7 prostate cell lines. We found very good concordance of the methylation levels between β-value and pyrosequencing. Gene expression analysis using qRT-PCR in a subset of 8 genes after treatment with 5-aza-2′-deoxycytidine and/or trichostatin showed up-regulation of gene expression in PCa cells. Quantitative analysis of 4 genes, SNRPN, SHANK2, MST1R, and ABCG5, in matched normal and PCa tissues derived from AA and Cau PCa patients demonstrated differential promoter methylation and concomitant differences in mRNA expression in prostate tissues from AA vs. Cau. Regression analysis in normal and PCa tissues as a function of race showed significantly higher methylation prevalence for SNRPN (P = 0.012), MST1R (P = 0.038), and ABCG5 (P < 0.0002) for AA vs. Cau samples. We selected the ABCG5 and SNRPN genes and verified their biological functions by Western blot analysis and siRNA gene knockout effects on cell proliferation and invasion in 4 PCa cell lines (2 AA and 2 Cau patients-derived lines). Knockdown of either ABCG5 or SNRPN resulted in a significant decrease in both invasion and proliferation in Cau PCa cell lines but we did not observe these remarkable loss-of-function effects in AA PCa cell lines. Our study demonstrates how differential genome-wide DNA methylation levels influence gene expression and biological functions in AA and Cau PCa.     

Comparison of remote versus in-person behavioral consultation for treatment of canine separation anxiety

To investigate the validity of remote consultation for treatment of canine separation anxiety, this study compared the efficacy of 2 types of behavioral services offered by Tufts Cummings School of Veterinary Medicine (TCSVM): (a) “PetFax,” a remote consultation service in which dog caregivers (owners) and a certified applied animal behaviorist correspond via fax or email and (b) in-person clinic consultation, which requires that owners bring their dogs to the Animal Behavior Clinic at TCSVM to consult with a board-certified veterinary behaviorist, a veterinary behavior resident, or a certified applied animal behaviorist. The study tested 4 variables for significant differences between PetFax users and clinic visitors: (a) pre- and posttreatment anxiety scores; (b) owner-reported improvement; (c) percentage of rehomed dogs, dogs relinquished or euthanized because of separation anxiety; and (d) clarity of communication with owners. The study found no significant differences between the groups. Difference scores and owner reports demonstrated substantial reduction in separation anxiety in both groups. Results indicate remote consultation is a valid way for behavioral professionals to share behavior modification advice with owners regarding canine separation anxiety.     

Ca2+, annexins, and GTP modulate exocytosis from maize root cap protoplasts

Protoplasts isolated from root cap cells of maize were shown to secrete fucose-rich polysaccharides and were used in a patch-clamp study to monitor changes in whole-cell capacitance. Ca2+ was required for exocytosis, which was measured as an increase in cell capacitance during intracellular dialysis with Ca2+ buffers via the patch pipette. Exocytosis was stimulated significantly by small increases above normal resting [Ca2+]. In the absence of Ca2+, protoplasts decreased in size. In situ hybridization showed significant expression of the maize annexin p35 in root cap cells, differ-entiating vascular tissue, and elongating cells. Dialysis of protoplasts with maize annexins stimulated exocytosis at physiological [Ca2+], and this could be blocked by dialysis with antibodies specific to maize annexins. Dialysis with milli-molar concentrations of GTP strongly inhibited exocytosis, causing protoplasts to decrease in size. GTPgammaS and GDPbetaS both caused only a slight inhibition of exocytosis at physiological Ca2+. Protoplasts were shown to internalize plasma membrane actively. The results are discussed in relation to the regulation of exocytosis in what is usually considered to be a constitutively secreting system; they provide direct evidence for a role of annexins in exocytosis in plant cells.     

Garlic attenuates histological and histochemical alterations in livers of Schistosoma mansoni infected mice

Interest in screening for new anti-schistosomal agents is growing because of increased concerns about resistance to and safety of praziquantel. We investigated the anti-schistosomal action of prophylactic and therapeutic doses of garlic on the histological and histochemical alterations caused by Schistosoma mansoni infection. Livers of infected mice were characterized by granulomas, periportal inflammation and fibrosis, hepatocyte vacuolation, fatty degeneration and necrosis, and hypertrophy and pigmentation of Kupffer cells. Significant depletion of carbohydrates and increased lipid vacuoles also were observed. All garlic regimens caused suppression of granuloma formation and amelioration of histological and histochemical changes; the continuous treatment protocol produced the best results. Garlic appears to be a safe and economical anti-schistosomal adjuvant for attenuating the pathogenicity of schistosomiasis.     

Extra-articular features in early rheumatoid disease.

One hundred and two patients who presented with rheumatoid disease within the first year of onset were studied prospectively every four months for a mean 4.5 years to assess the incidence of extra-articular features. The features that seemed to be common in the early stages included hand-muscle wasting, carpal tunnel syndrome, lymphadenopathy, non-specific ankle swelling, and rheumatoid nodules, and to a lesser extent hepatomegaly, being underweight, conjunctivitis, skin transparency, and a palpable thyroid gland. Those features which seldom occurred early included scleromalacia, temporal artery inolvement, salivary gland enlargement, distal-motor neuropathy, splenomegaly, digital vasculitis, and pulmonary and cardiac complications. Being underweight indicated a significantly more severe outcome.     

Clinical and Laboratory Double-blind Investigation on Effect of Fibrinolytic Therapy in Patients with Cutaneous Vasculitis

The effects of phenformin and ethyloestrenol and phenformin and stanozolol on the clinical state, plasma fibrinolytic activity, and fibrinogen-fibrin-related antigen (F.R.-antigen) were compared with placebo in 13 patients with cutaneous vasculitis. Eight patients showed considerable clinical improvement when taking phenformin and an anabolic steroid; an impaired fibrinolytic activity before treatment favoured clinical improvement.     

Distribution and abundance of African waterfowl: examples from the African Waterfowl Census

Dodman, T. & Rose, P. 2000. Distribution and abundance of African waterfowl: examples from the African Waterfowl Census. Ostrich 71 (1 & 2): 235–243.

Wetlands International coordinates waterfowl counts in Africa. Counts from 1958–1990 were analysed in 1991, when the African Waterfowl Census (AfWC) was also launched. By 1996, 25 countries were participating. This preliminary appraisal of the AfWC shows that resulting data can be used to identify distribution and abundance patterns, although there are still significant gaps in AfWC coverage and focus. The degree to which AfwC data may be used to assess the conservation status of African waterfowl populations depends on a function of data quality, quantity and reliability. To enable this practical use of data, several priorities for future work are identified, based on the strengths and weaknesses of the current information: (1) simultaneous co-ordinated counts, (2) regular annual or biannual monitoring of the same sites, (3) development of priority list of sites for regular survey, (4) frequent monitoring of particularly important sites (e.g. every three months), (5) building waterbird surveys into broader programmes of ecological monitoring, (6) planning of special internationally coordinated surveys, (7) planning regular complete surveys in major wetlands, e.g. every five years, and (8) extending the AfWC to other taxa and broader surveys of wetland use by man. In Africa, 522 discrete waterbird populations have been identified. Over half the populations for which trends have been established are in decline. Results from a recent atlas of Anatidae are illustrated by the Fulvous Whistling-Duck Dendrocygnu bicolor, for which three discrete populations and 21 key sites are identified. Wetlands are the most important habitats for waterbirds. Many species (e.g. Grey Heron Ardea cinema) exploit a variety of wetland types and are geographically widespread; those with special habitat requirements (e.g. Blue-winged Goose Cyanochen cyanopterus) oh have restricted ranges. Hartlaub's Duck Pteronetta hartlaubi is one of the few waterbirds specific to the tropical forest biome. The movements of Abdim's Stork Ciconia abdimii in southern Africa show a clear response to rainfall.