Investigation of factors influencing drug release using calcium alginate polymer

The effects of mixing, the sodium alginate concentration, and calcium chloride concentration on the release of sulphamethoxazole (model drug) impregnated in calcium alginate beads were investigated and evaluated. The release behaviour of the sulphamethoxazole from the calcium alginate beads was studied in a 0.1N HCl aqueous solution at 37v°C. The release rate of the sulphamethoxazole depends heavily on the type of mixers during the formation of the drug-alginate beads. The highest release rate was achieved when four-bladed rectangular agitator was used while the lowest release was achieved when magnetic stirrer was used. The amount of the released sulphamethoxazole varies slightly with the variation of the alginate concentration. The total release of sulphamethoxazole when 1% w/v solution of sodium alginate was used found to be 80% of the total drug content while 72% and 68% of the total drug content for 1.5% and 2% sodium alginate solutions. Three different calcium chloride concentrations were used (i.e., 5%, 10%, and 15% CaCl₂). The effect of the calcium chloride concentration on the release of the sulphamethoxazole is very pronounced.     

The different banding patterns produced by restriction endonuclease digestion in mitotic chromosomes of the American and European eel

The detection of three classes of C-heterochromatin by in situ restriction endonuclease digestion allowed a karyotype differentiation between the American and the European eel.     

Contrast-FEL—A Test for Differences in Selective Pressures at Individual Sites among Clades and Sets of Branches

A number of evolutionary hypotheses can be tested by comparing selective pressures among sets of branches in a phylogenetic tree. When the question of interest is to identify specific sites within genes that may be evolving differently, a common approach is to perform separate analyses on subsets of sequences and compare parameter estimates in a post hoc fashion. This approach is statistically suboptimal and not always applicable. Here, we develop a simple extension of a popular fixed effects likelihood method in the context of codon-based evolutionary phylogenetic maximum likelihood testing, Contrast-FEL. It is suitable for identifying individual alignment sites where any among the K≥2 sets of branches in a phylogenetic tree have detectably different ω ratios, indicative of different selective regimes. Using extensive simulations, we show that Contrast-FEL delivers good power, exceeding 90% for sufficiently large differences, while maintaining tight control over false positive rates, when the model is correctly specified. We conclude by applying Contrast-FEL to data from five previously published studies spanning a diverse range of organisms and focusing on different evolutionary questions.     

Effect of precursors on biosynthesis of monensins A and B

Precursors of monensins (acetate, propionate, butyrate, isobutyrate) affect the total production and the relative proportion of monensins A and B. Addition of propionate into the fermentation medium causes a prevalence of monensin B whereas butyrate and isobutyrate stimulate the production of monensin A and suppress the production of monensin B.     

Role of adrenergic structures in regulating the release by the intestines of hemocoagulating compounds into the blood stream

Experiments on cats were made to study the capability of adrenaline, tropaphen and propranolol of influencing the intensity of the release of hemocoagulating compounds and anticoagulants from the intestinal vessels and tissues to the bloodstream (perfusate). Adrenaline was found to increase the coagulative activity of the perfusate, provoking an enhanced release into it of thromboplastin, an analogue of plasma factor V and antiheparin compounds and suppressing the release of antithromboplastins. The blockade of the alpha-adrenoreceptors was accompanied by a dramatic increase of antithromboplastins to the intestinal perfusate, whereas the depression of the activity of beta-adrenergic structures by reduction of the release of tissue thromboplastin inhibitors. It is concluded that regulation of the release of antithromboplastins in the intestine is mediated by the structures similar in their characteristics to alpha- and beta-adrenoreceptors.     

Modulating effect of cerulein on benzodiazepine receptors

Subcutaneous administration of caerulein (100-500 micrograms/kg) significantly reduced the development of picrotoxin (8 mg/kg) seizures in male mice. The same doses of caerulein inhibited 3H-flunitrazepam binding in in vivo experiments. Proglumide, an antagonist of cholecystokinin receptors, in low dose (5 mg/kg) potentiated the effects of caerulein (100 micrograms/kg), whereas the administration of proglumide in high dose (25 mg/kg) reduced the action of caerulein on 3H-flunitrazepam binding and picrotoxin seizures. Caerulein (5-1000 nM) decreased 3H-flunitrazepam binding in in vitro experiments only after supplementation of the binding medium with 120 mM NaCl and 5mM KCl. The results suggest the possible interaction of caerulein with chloride ionophor. It seems probable that the direct interaction of caerulein with chloride ionophor in involved in the inhibitory effect of caerulein on picrotoxin seizures and 3H-flunitrazepam binding.