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.     

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.     

Amphiphilic cationic peptides mediate cell adhesion to plastic surfaces

Four amphiphilic peptides, each with net charges of +2 or more at neutrality and molecular weights under 4 kilodaltons, were found to mediate the adhesion of normal rat kidney fibroblasts to polystyrene surfaces. Two of these peptides, a model for calcitonin (peptide 1, MCT) and melittin (peptide 2, MEL), form amphiphilic alpha-helical structures at aqueous/nonpolar interfaces. The other two, a luteinizing hormone-releasing hormone model (peptide 3, LHM) and a platelet factor model (peptide 4, MPF) form beta-strand structures in amphiphilic environments. Although it contains only 10 residues, LHM mediated adhesion to surfaces coated with solutions containing as little as 10 pmoles/ml of peptide. All four of these peptides were capable of forming monolayers at air-buffer interfaces with collapse pressures greater than 20 dynes/cm. None of these four peptides contains the tetrapeptide sequence Arg-Gly-Asp-Ser, which has been associated with fibronectin-mediated cell adhesion. Ten polypeptides that also lacked the sequence Arg-Gly-Asp-Ser but were nonamphiphilic and/or had net charges less than +2 at neutrality were all incapable of mediating cell adhesion (Pierschbacher and Ruoslahti, 1984). The morphologies of NRK cells spread on polystyrene coated with peptide LHM resemble the morphologies on fibronectin-coated surfaces, whereas cells spread on surfaces coated with MCT or MEL exhibit strikingly different morphologies. The adhesiveness of MCT, MEL, LHM, and MPF implies that many amphiphilic cationic peptides could prove useful as well defined adhesive substrata for cell culture and for studies of the mechanism of cell adhesion.     

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.     

Diet of the Indochinese silvered langur (Trachypithecus germaini) in Kien Luong Karst area,Kien Giang Province

The Indochinese silvered langur (Trachypithecus germaini) is distributed to the west of Mekong River in Cambodia, Lao PDR, Thailand and Vietnam. During a two‐year study, from May 2014 to May 2016, we collected 320.44 hr of behavior, with 17,040 feeding bouts recorded (142 hr) for T. germaini on Chua Hang Karst Mountain, Kien Luong District, Kien Giang Province, Vietnam. Feeding accounted for 45% of the Indochinese silvered langurs’ activity budget. The plant diet of the Indochinese silvered langurs was principally composed of young leaves (58%), followed by mature leaves (9.5%), fruits (22.7%), flowers (4.7%), buds (3.3%), petioles (1.2%), and other (0.5%). A total of 58 plant species were fed on by the silvered langurs, and leaves of eight species (Phyllathus reticulatus, Ficus rumphii, Ficus tinctoria, Ficus microcarpa, Cayratia trifolia, Streblus ilicifolia, Combretum latifolium, and Streblus asper) were fed on throughout the year. P. reticulatus was most frequently eaten (13.9% feeding time, n = 1,733). Food selection differed significantly between months and seasons. The Indochinese silvered langurs ate 27 plant species in the wet season compared with 23 plant species in the dry season. Leaf chemical composition of two food categories, 16 eaten species (with 10 most frequently consumed species and six least consumed species), and four noneaten species, were analyzed. Feeding samples from eaten species in the Indochinese silvered langurs's diet contained lower amounts of condensed tannin, lignin, protein, ash, and lipids, but a higher amount of total sugar compared with samples from noneaten species. Furthermore, the most frequently consumed species contained lower amounts of lignin compared with the less frequently consumed species. Using a generalized linear model with five variables, including neutral detergent fiber (NDF), total sugar, lignin, lipid, and calcium (Ca) indicated that NDF positively correlated and lignin content negatively correlated with feeding records in the diet of these langur.     

Reinnervation of experimental superficial wounds in rats

Sensory reinnervation of a superficial skin wound in the rat was studied by labeling sensory axons with anterogradely transported wheat germ agglutinin-horseradish peroxidase. Reinnervation starts after 3 days from the edge of the wound as well as from beneath the wound. About 2 weeks after the production of the wound, some hyperinnervation appears to be present, but after a few additional weeks, the innervation pattern is essentially normal. The results indicate that structural recovery of sensory axons is rapid and probably complete when skin wounds heal with no or minimal scar formation.