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Biomedical subjects

K Andersen

Publications and source records attributed to K Andersen.

At least 163 records · Page 9Linked to original sources
PubMed1978

Egg size and form as taxonomic criteria in Diphyllobothrium (Cestoda, Pseudophyllidea).

The size and form (length, width, and length: width ratio) of eggs of Diphyllobothrium dendriticum, D. ditremum and D. latum vary considerably among individual worms within each species. The size of eggs varies with host species and a decrease in egg size with increasing intensity of infestation is indicated. The egg size of D. latum increases during the first 10-12 days of egg production. For single worm infections in golden hamsters the mean egg length and width of D. ditremum are significantly smaller than the corresponding means of D. dendriticum and D. latum, while D. latum has significantly wider eggs than D. dendriticum. As taxonomic characteristics, egg size and form may contribute to species delimitation at the population level. For identification at the individual level the best possible accuracy is about 80%. This accuracy is considerably reduced when variation in host species and intensities of infestations are introduced. Scanning electron microscope studies did not reveal any differences among eggs of the three species.

Animals↗
PubMed1978

The development of the tapeworm Diphyllobothrium latum (L. 1756) (Cestoda; Pseudophyllidea) in its definitive hosts, with special references to the growth patterns of D. dendriticum (Nitzsch, 1824) and D. ditremum (Creplin, 1827).

When Diphyllobothrium latum develops from larva to adult in a definitive host, it first sheds the entire larval 'body' before growth of an adult strobila starts. This process of shedding off the entire larval abothrial extremity, piece by piece, takes about 48 h. By this time the larva has usually reached the anterior third of the small intestine of the host. D. dendriticum and D. ditremum develop quite differently, although exhibiting similar anterior migrations. In these two species the larvae develop directly into adults without the larval 'body' first being shed. The implications of the observed differences in growth pattern between these three species of Diphyllobothrium to the classification of diphyllobothriid cestodes is discussed briefly.

Aging↗
PubMed1977

A marine Diphyllobothrium plerocercoid (cestoda, pseudophyllidea) from blue whiting (micromestius poutasson).

A type of Diphyllobothrium plerocercoid found in blue whiting, Micromestius poutasson, caught near the north edge of the Faeroe Banks, is described. The most dominant characters of these larvae are their typical dorsoventrally flattened body and their fully extruded and "adult"-like scolex. A morphological comparison with perocercoids of D. dendriticum, D. ditremum and D. latum is given.

Animals↗
PubMed1977

Energetics of biological nitrogen fixation: determination of the ratio of formation of H2 to NH4+ catalysed by nitrogenase of Klebsiella pneumoniae in vivo.

Nitrogen fixation (Nif)-derepressed mutants of Klebsiella pneumoniae consumed, under optimum conditions, 7.5 to 8.5 mol glucose per mol N2 fixed. The nitrogenase system of these mutants catalysed the production of about 1.3 mol H2 per mol N2 reduced. Almost one-third of the energy as ATP and reductant used by nitrogenase in vivo may be lost in H2 production, since an ATP/2e ratio of approximately 4 was obtained. Nitrogenase-catalysed H2 production was not substantially suppressed by increasing the partial pressure of N2 from 0.2 atm (20 kPa) to 1 atm (101 kPa). In the absence of N2, H2 production catalysed by nitrogenase increased about threefold. It is concluded that nitrogenase-catalysed H2 production is of major importance in the overall efficiency of biological N2 fixation in vivo.

Catalysis↗
PubMed1977

Uncontrollable hemorrhage and tissue adhesive.

A case is reported of uncontrollable hemorrhage from suture lines in a patient having undergone coronary surgery. Ultimately the bleeding was brought under control by the use of isobutyl-cyanoacrylate. A piece of fascia was affixed to the suture line. Tissue adhesive is a valuable tool in difficult hemostatic situations, and should be available where major surgery is performed.

Adult↗
PubMed1976

The occurrence of a "SME"-defect-like abnormality in the head of spermatozoa from a Norwegian Landrace boar.

A spermhead-defect appearing in 15-20 per cent of the spermatozoa from a Norwegian Landrace boar with a slightly impaired fertility was studied in light and electron microscope. The defect had the shape of a circumferential, somewhat elevated area containing a cystic structure located within the nucleus. In some of the sections observed in electron microscope a communication could be found between the cyst and the acrosome, indicating that a deviating development of the latter could be involved in the formation of the defect. In some spermatozoa the occurrence of the cyst was combined with the presence of an apical defect of the acrosome. From ultrastructural studies of spermatids the development of the cystic defect was found to have reached a rather advanced stage early in the acrosome-phase of the spermateliosis. As a whole the observations correspond very well with those made in connection with the socalled "SME"-defect first found in a Danish Landrace boar.

Acrosome↗
PubMed1975

Ultrastructural studies on Diphyllobothrium ditremum and D. dendriticum (Cestoda, Pseudophyllidea), with emphasis on the scolex tegument and the tegument in the area around the genital atrium.

The scolices of D. ditremum and D. dendriticum are similar in regard to general morphology and ultrastructure of the tegument. At the scolex apex and along the upper bothrial edges sensory endings are numerous. The inner bothrium surface of D. ditremum appears to be plain or smooth, the distal cytoplasm is only about 0.6 mum thick and covered with long and slender microtriches. When D. ditremum is attached to the host gut an adhesive layer of secreted substance exists between the inner bothrium surface and the host intestinal villi. In D. dendriticum, however, no secreted layer exists between the inner bothrium surface and the host intestinal villi and the inner bothrium surface of this species appears to be lobed or lappet formed. The lobes are protrusions of the distal cytoplasm and are covered with long and slender microtriches. Large conglomerations of secretion globules appearing to be enclosed by a double membrane, are observed in the scolices of D. dendriticum and D. ditremum, although more frequent in the latter. Differences existing between the distal cytoplasm of the scolex and the gravid proglottid are described. The papillae around the genital atrium in mature and gravid segments were studied. Each papilla appears as a thickening of the distal cytoplasm, which in this region is 10-12 mum thick, when studied with transmission electron microscope. From the area between the papillae sensory endings appearing in sections to be either single, double or triple are described.

Animals↗
PubMed1975

Purification and characterization of guinea-pig intestinal brush borders.

The purification of guinea-pig intestinal brush borders by a rapid sucrose-gradient-centrifugation step is reported. A 29-fold increase in the maltase/DNA quotient indicates considerable purification of the brush borders from nuclei. The biological activity of the brush borders was well preserved, as demonstrated by a high recovery of human gastric-juice-mediated uptake of 57Co-labelled vitamin B-12; homogeneity and purity were confirmed by scanning electron microscopy. Both the morphological appearance and biological activity were unchanged after prolonged storage in glycerol.

Animals↗