The effect of sulfated polysaccharides on the free intracellular calcium ion concentration of lymphocytes

Recent studies have demonstrated that murine lymphocytes express specific cell-surface receptors for a range of sulfated polysaccharides. In order to determine whether polysaccharide binding induces transmembrane signaling, the effects of sulfated polysaccharides on the free intracellular calcium ion concentration [( Ca2+]i) of mouse thymocytes and spleen cells were determined. Cells were loaded with Indo-I, a fluorescent indicator of calcium ion concentration. The validity and limitations in the use of this indicator in the determination of [Ca2+]i are documented. Dextran sulfate (Mn = 500,000), iota-carrageenan, lambda-carrageenan and kappa-carrageenan all cause relatively large changes in the [Ca2+]i of thymocytes (change in [Ca2+]i greater than 50 nM). Of these, dextran sulfate (Mn = 500,000) always had the greatest effect on [Ca2+]i. Smaller responses were obtained with heparin and dextran sulfate (Mn = 5000), while no response was obtained with chondroitin 4-sulfate, chondroitin 6-sulfate, pentosan sulfate or fucoidin. This response pattern (with the exception of fucoidin and pentosan sulfate) corresponds with the expression of thymocyte receptors for these polysaccharides. The increase in [Ca2+]i caused by the sulfated polysaccharides requires extracellular Ca2+ ions however, it is unlikely that voltage-dependent ion channels are involved in these responses. In contrast to thymocytes, although spleen cells express receptors for sulfated polysaccharides, they were unresponsive to all of the sulfated polysaccharides tested, suggesting a basic difference between thymocytes and peripheral T and B lymphocytes in their response to the binding of sulfated polysaccharides.     

Functional anatomy of the human saccus lacrimalis

The relations between the saccus lacrimalis and different portions of the musculus orbicularis oculi were studied in orbital regions of human fetuses sectioned into numbered series. No insertions of the pars lacrimalis or Horner's muscle on the saccus were found. These muscular fibres pass along the dorsal wall of the saccus and are separated from it by the reflex tendon of the ligamentum palpebrale mediale. The only muscular fibres that insert on the saccus are those that approach the anterior face of the saccus and the fornix. The fibres that insert on the anterior face proceed from the deep bundles of the pars preseptalis of the lower eyelids, and those that insert on the fornix derive from the deep bundles of the pars preseptalis of the upper eyelid.     

Two new species of Haptoglossa from north-east England

Two new species of Haptoglossa , one zoosporic, H. northumbrica , and one aplanosporic, H. polymorphs, , were isolated from samples of manure and horse dung in north-east England. The zoosporic H. northumbrica is morphologically similar to H. dickii but differs in having slightly smaller infection gun cells with a unique internal arrangement of cones in the apical missile chamber. The thallus of the aplanosporic H. polymorpha is similar to H. heteromorpha but produces three different types of aplanospore. The smaller cysts either develop into broad, arcuate gun cells or form curved adhesive cells that have a rounded base. These curved adhesive cells have very different internal ultrastructural organization. The large cysts develop into infection cells that are morphologically similar to the curved adhesive cells, but their internal structure has not yet been observed.     

Oxygen Transport System in Children Living in the Russian Far North

We studied 654 healthy ten- to twelve-year-old children living in the Russian Far North (Taimyr peninsula) and in Siberia (town of Krasnoyarsk). The state of the body oxygenation and the systems responsible for oxygen delivery were studied according to the length of time living in the Russian Far North and season of the year. An examination of newcomer children revealed the following changes during the first year of living in the Russian Far North: an increased respiration rate and changes in its circadian rhythm; an increase in the heart rate, cardiac output, and cardiac index; an increase in the mean corpuscular volume in the red blood system; the activation of lipid peroxidation, and the changes in electrolyte balance of cells. The control mechanisms of oxygen transport system gradually stabilized during the ages of two to five years. In children living more than five years in the Russian Far North, the increased oxygen demand was met by the activation of cardiovascular and red blood systems aimed at more effective and adequate oxygen delivery to tissues.     

Lipase-catalyzed transamidation of non-activated amides in organic solvent

A novel biocatalytic reaction of transamidation of non-activated amides with amines is reported. Among 45 different lipolytic and proteolytic enzymes tested, only the lipase from Candida antarcticawas able to catalyze this reaction. The reaction proceeded with up to ca. 80% conversion in anhydrous methyl tert-butyl ether and worked with both N-substituted and unsubstituted amides. The biocatalytic transamidation is an equilibrium process and, therefore, higher conversions to the desired amide were achieved by using increased concentrations of the amine nucleophile.