Effects of oral zinc gluconate on glucose effectiveness and insulin sensitivity in humans

Zinc improves both insulin secretion and insulin sensitivity, and exerts insulin-like effects. We investigated its acute effects on the parameters of glucose assimilation determined with the minimal model technique from frequent sampling intravenous glucose tolerance test (FSIVGTT) in seven healthy volunteers. FSIVGTTs (0.5 g/kg of glucose, followed by 2 U insulin iv injection at 19 min) were performed after the subjects had taken 20 mg zinc gluconate twice (the evening before and 30 min before the beginning of the test) or placebo pills (simple blind randomized protocol). Glucose assimilation was analyzed by calculating Kg (slope of the exponential decrease in glycemia), glucose effectiveness Sg (i.e., ability of glucose itself to increase its own disposal independent of insulin response), and SI (insulin sensitivity, i.e. the effect of increases in insulinemia on glucose disposal). The two latter parameters were calculated by fitting the experimental data with the two equations of Bergman’s “minimal model”. Zinc increased Kg (p<0.05) and Sg (p<0.05), whereas SI and insulin first-phase secretion did not significantly increase. This study suggests that zinc improves glucose assimilation, as evidenced by the increase in Kg, and that this improvement results mainly from an increase in glucose effectiveness (insulin-like effect), rather than an action on insulin response or insulin sensitivity.     

Polymorphism in the Ostertagiinae Lopez-Neyra, 1947 and comments on the systematics of these nematodes

A list of 19 polymorphic species of the generaOstertagia, Orloffia, Teladorsagia, Marshallagia andSpiculopteragia is presented. The morphs of the polymorphic species in question have identical females and show similarities in some male features, e.g. the structure of the oesophagus, the synlophe and the shape of the rays of the copulatory bursa. However, they differ by characters which are recognised as generic features, e.g. the structure of spicules, gulbernaculum and genital cone. The presence or lack of minor morphs is a generic feature in the Ostertagiinae. Each polymorphic genus has a defined type of minor morph.     

Efficient gene targeting in the moss Physcomitrella patens

The moss Physcomitrella patens is used as a genetic model system to study plant development, taking advantage of the fact that the haploid gametophyte dominates in its life cycle. Transformation experiments designed to target three single-copy genomic loci were performed to determine the efficiency of gene targeting in this plant. Mean transformation rates were 10-fold higher with the targeting vectors and molecular evidence for the integration of exogenous DNA into each targeted locus by homologous recombination is provided. The efficiency of gene targeting determined in these experiments is above 90%, which is in the range of that observed in yeast and several orders of magnitude higher than previous reports of gene targeting in plants. Thus, gene knock-out and allele replacement approaches are directly accessible to study plant development in the moss Physcomitrella patens . Moreover, efficient gene targeting has so far only been observed in lower eukaryotes such as protozoa, yeasts and filamentous fungi, and, as shown here the first example from the plant kingdom is a haplobiontic moss. This suggests a possible correlation between efficient gene targeting and haplo-phase in eukaryotes.     

Physical and genetic characterization of the IncI plasmid R144-drd3

A physical and genetic map of the IncI plasmid R144-drd3 was obtained by determining restriction endonuclease sites and by physical and genetic analysis of cloned fragments, of Tn1 insertion mutants and of deletion mutants.     

Preparation of isolated liver endothelial cells and Kupffer cells in high yield by means of an enterotoxin

A new method for preparing non-parenchymal rat liver cells (NPC) is described. The liver cell suspension, prepared by perfusing the liver with collagenase, was treated with enterotoxin from Clostridium perfringens for 15 min. The enterotoxin made the parenchymal cells leaky, and these cells could be separated from the NPC by centrifugation in a solution containing Nycodenz (20%, w/v). During the centrifugation, the NPC floated, while the parenchymal cells sedimented. The yield of NPC per liver (200 g rat) was about 250 X 10(6) cells. The NPC were further separated into endothelial cells, Kupffer cells and stellate cells by centrifugal elutriation. This method was particularly useful for preparing endothelial cells in high yield (100 X 10(6) cells per liver). Intravenously injected formaldehyde-treated albumin was selectively taken up by the endothelial cells. Isolated endothelial cells in suspension as well as in surface culture maintained their ability to endocytose this ligand.     

Studies in vitro on the uptake and degradation of sodium hyaluronate in rat liver endothelial cells.

Rat liver endothelial cells in primary cultures at 7 degrees C bind radioactively labelled sodium hyaluronate (HA; Mr 400 000) specifically and with high affinity (Kd = 6 X 10(-11) M). Maximal binding capacity is approx. 10(4) molecules per cell. Inhibition experiments with unlabelled HA and oligosaccharides from HA indicate that each molecule is bound by several receptors acting co-operatively and that the single receptor recognizes a tetra- or hexa-saccharide sequence of the polysaccharide. At 37 degrees C the liver endothelial cells endocytose the HA. The process combines the features of a receptor-mediated and a fluid-phase endocytosis. The rate of internalization does not show any saturation with increasing HA concentration, but is approximately proportional to the polysaccharide concentration at and above the physiological concentration. At 50 micrograms of free HA/l each liver endothelial cell accumulates 0.1 fg of the polysaccharide/min. Fluorescent HA accumulates in perinuclear granules, presumably lysosomes. Degradation products from HA appear in the medium about 30 min after addition of the polysaccharide to the cultures. The radioactivity from HA containing N-[3H]acetyl groups or 14C in the sugar rings is recovered mainly as [3H]acetate and [14C]acetate respectively. Estimations of the capacity of liver endothelial cells to internalize and degrade HA in vitro indicate that these cells may be primarily responsible for the clearance of HA from human blood in vivo.     

Polarization and fluorescent microscopy —Simple methods for demonstrating pulmonary surfactant lipids

Summary Birefringence and fluorochrome lipid staining with benzpyrene are demonstrated as simple morphological methods to reveal the presence or absence of surfactant lipids in human newborn lung tissue. Lack of lipid birefringence proves to be an associated finding in the lungs of premature infants with hyaline membrane disease, indicating the possible pathogenetical importance of surfactant deficiency.