The increased population of the Wild Boar (Sus scrofa L.) in Europe

In this paper the recent population changes of the Wild Boar in different European countries is analysed through the study of hunting statistics. A simultaneous increase in numbers is observed throughout the whole area during the period 1965–1975. From 1975 onwards the population stabilizes itself apart from in peripheral areas like Finland. Potentially favourable factors which play a part in this process are discussed and certain reproductive and dispersive characteristics which favour its invasive behaviour are discussed.     

Testosterone alters duodenal calcium transport and longitudinal bone growth rate in parallel in the male rat.

Duodenal active calcium transport and longitudinal bone growth rate have been shown previously to be regulated in parallel by alteration of gonadal hormone status in sexually maturing female rats. The present study was designed to extend these observations to the sexually maturing male rat. Male rats were orchidectomized (ORX) and given Silastic implants containing either testosterone or estradiol at 6 weeks of age. At 9 weeks of age, duodenal active calcium transport was measured by the everted gut sac method and longitudinal bone growth rate was determined by tetracycline labeling. Decreases in body weight, longitudinal bone growth rate, duodenal calcium transport, and serum Ca and P were exhibited by ORX animals as compared with age-matched control animals. Testosterone administration to ORX animals resulted in an increase in body weight, longitudinal bone growth rate, duodenal calcium transport, and serum Ca and P as compared with ORX animals to a level not significantly different from that of age-matched control animals. Estradiol administration to ORX animals resulted in an additional decrease in body weight, although no significant effect on duodenal calcium transport, serum Ca, or P was noted as compared with ORX animals. There were no statistically significant alterations in the circulating levels of 1,25-dihydroxyvitamin D, parathyroid hormone, or osteocalcin in response to any of the experimental manipulations of gonadal status. These results indicate that, as in the female, gonadal hormone status affects intestinal calcium transport in sexually maturing male rats in parallel with changes in bone growth rate by mechanisms that are independent of circulating levels of 1,25-dihydroxyvitamin D.     

Why Doesn't the Creed Read "Always Be Critical"? An Examination of a Liberal Curriculum

Using ethnographic data collected in a second grade classroom over the course of a school year, this paper describes the ways in which one school's discourse of liberalism is deleteriously deployed. We view the school's discipline creed as emblematic of the school's liberal curriculum, and interrogate the effects on four African American boys in the classroom when the school enacts this creed. Despite the agency that these boys obviously had, they were unable to control the ways in which they were placed at a structural disadvantage and manipulated by a system far more powerful than they were. The results were that these four boys suffered. Not only did the intended liberal curriculum fail to be translated fully into the enacted curriculum, the liberal underpinnings of this curriculum precluded teachers and students from taking any critical stance.     

Lipid asymmetry induced by transmembrane pH gradients in large unilamellar vesicles

We have investigated the influence of transmembrane pH gradients across large unilamellar vesicle membranes on the transbilayer distributions of simple lipids with weak base and weak acid characteristics. Trinitrobenzenesulfonic acid labeling results consistent with a rapid and complete migration of stearylamine and sphingosine to the inner monolayer of the large unilamellar vesicles are observed when the large unilamellar vesicles' interior is acidic. Alternatively, when the vesicle interior is basic, oleic and stearic acid cannot be removed by external bovine serum albumin, indicating a localization in the inner monolayer. Moreover, effects corresponding to the decrease in external surface charge predicted upon the migration of stearylamine or stearic acid to the inner monolayer are readily detected employing ion exchange chromatography. These results are consistent with transbilayer distributions of these agents dictated by a Henderson-Hasselbach equilibrium. The possible implications for metabolic regulation by pH gradients, as well as factors giving rise to phospholipid transbilayer asymmetry, are discussed.     

Vesicles of variable sizes produced by a rapid extrusion procedure

Previous studies from this laboratory have shown that large unilamellar vesicles can be efficiently produced by extrusion of multilamellar vesicles through polycarbonate filters with a pore size of 100 nm (Hope, M.J., Bally, M.B., Webb, G. and Cullis, P.R. (1985) Biochim. Biophys. Acta 812, 55-65). In this work it is shown that similar procedures can be employed for the production of homogeneously sized unilamellar or plurilamellar vesicles by utilizing filters with pore sizes ranging from 30 to 400 nm. The unilamellarity and trapping efficiencies of these vesicles can be significantly enhanced by freezing and thawing the multilamellar vesicles prior to extrusion. This procedure is particularly applicable when very high lipid concentrations (400 mg/ml) are used, where extrusion of the frozen and thawed multilamellar vesicles through 100 and 400 nm filters results in trapping efficiencies of 56 and 80%, respectively. Freeze-fracture electron microscopy revealed that vesicles produced at these lipid concentrations exhibit size distributions and extent of multilamellar character comparable to systems produced at lower lipid levels. These results indicate that the freeze-thaw and extrusion process is the technique of choice for the production of vesicles of variable sizes and high trapping efficiency.     

Techniques for encapsulating bioactive agents into liposomes

As a prerequisite for the use of liposomes for delivery of biologically active agents, techniques are required for the efficient and rapid entrapment of such agents in liposomes. Here we review the variety of procedures available for trapping hydrophilic and hydrophobic compounds. Considerations which are addressed include factors influencing the choice of a particular liposomal system and techniques for the passive entrapment of drugs in multilamellar vesicles and unilamellar vesicles. Attention is also paid to active trapping procedures relying on the presence of (negatively) charged lipid or transmembrane ion gradients. Such gradients are particularly useful for concentrating lipophilic cationic drugs inside liposomes, allowing trapping efficiencies approaching 100%.     

Pullulanase synthesis in Klebsiella (Aerobacter) aerogenes strains growing in continuous culture

1. Pullulanase synthesis was studied in 16 classified (N.C.I.B.) strains and in an industrial strain (R) of Klebsiella aerogenes grown in chemostats containing maltose as inducer and sole carbon source. 2. Maximum synthesis was associated with carbon-limited growth at a low dilution rate (about 0.2h(-1)). The enzyme remained firmly cell-bound and seemed to be located on the cell surface. 3. Three strains had high activity (R, N.C.I.B. 5938, 8017), twelve were intermediate, and two (N.C.I.B. 8153, 9146) had negligible activity but were inducible with pullulan. 4. Pullulan similarly induced low, but adequate, activity in the other strains in conditions (nutrient limitation other than carbon-limitation) in which pullulanase was otherwise very seriously repressed. Nevertheless, in carbon limitation pullulan induced no more enzyme than did maltose, maltotriose or oligosaccharide mixtures, and ;hyperactivity' never developed on protracted culture. 5. Cyclic AMP relieved the transient repression produced by adding glucose to maltose-limited cultures and a further change to glucose-limited conditions led to constitutive pullulanase synthesis. 6. Amylomaltase and alpha-glucosidase activities were also examined but in less detail. 7. The presence of pullulanase in maltose-limited growth is discussed, but no clear function can be assigned to it at present. The molar growth yields for all the strains were very similar, and no correlation was found between the overgrowth of one strain by another and pullulanase activity. Further, any function as a general branching enzyme in polysaccharide synthesis seems unlikely.     

The dimerization of Δ1-piperidine-2-carboxylic acid

The l-amino acid oxidase of Mytilus edulis has been used to oxidize l-lysine on a large scale in the presence of catalase. The alpha-oxo acid derived from lysine cyclizes to a Schiff base, which readily dimerizes. The dimer undergoes spontaneous dehydration and decarboxylation to form 1,2,3,4,5,6,7,8-octahydropyrido[3,2-a]-indolizin-10(4bH)-one. This structure was established by a study of its molecular weight and infrared, nuclear-magnetic-resonance and mass spectra.