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Ribonucleotide reduction is the only known biological means for de novo production of deoxyribonucleotides, the building blocks of DNA. These are produced from ribonucleotides, the building blocks of RNA, and the direction of this reaction has been taken to support the idea that, in evolution, RNA preceded DNA as genetic material. However, an understanding of the evolutionary relationships among t
We have investigated the effects of the novel imidazoline compound (+)-2-(2-(4,5-dihydro-1H-imidazol-2-yl)-thiopene-2-yl-ethyl)pyridine (NNC77-0074) on stimulus-secretion coupling in isolated pancreatic alpha- and beta-cells. NNC77-0074 stimulated glucose-dependent insulin secretion in intact mouse pancreatic islets. No effect was observed at less than or equal to 2.5 mM glucose and maximal stimul
[GRAPHIC] Two independent synthetic routes, starting from 1,3-cyclohexadione, toward the 4-hydroxy bicyclo[2.2.2]octane-2,6-dione derivative 3 are described.
A systematic comparison of the effect of architectural modifications to the network structure on the internal microstructure of N-isopropylacrylamide (NIPA) based hydrogels showed that the addition of a second component to the network significantly increased the proportion of macropores in the network. The second components considered were short poly(N-isopropylacrylamide)(PNIPAM) chains grafted t
1. Net primary production (NPP) by terrestrial ecosystems appears to be proportional to absorbed photosynthetically active radiation (APAR) on a seasonal and annual basis. This observation has been used in 'diagnostic' models that estimate NPP from remotely sensed vegetation indices. In 'prognostic' process-based models carbon fluxes are more commonly integrated with respect to leaf area index ass
During liquefaction of the ejaculate, the semen coagulum proteins semenogelin I (SEMG1) and semenogelin II (SEMG2) are degraded to low molecular mass fragments by kallikrein-related peptidase 3 (KLK3), also known as prostate-specific antigen. Semenogelin molecules initiate their own destruction by chelating Zn2+ that normally would completely inhibit the proteolytic activity of KLK3. In a similar
Using a statistical methodology, we aimed to identify a group of probable cases of oculo-auriculo-vertebral (OAV) dysplasia and to investigate possible relationships between different patterns of congenital malformations. Among 5,260 infants with multiple malformations collected from 4 large registers of congenital malformations, we identified 312 probable OAV cases. With the same technique, we ha
Collagen induced arthritis (CIA) is a common mouse model for rheumatoid arthritis. Two sets of truncated peptides derived from type II collagen have been prepared and tested for binding to A(q), a MHC-II molecule associated with development of CIA. Binding to A(q) correlated well with predictions from a computer-based model. T-cell hybridomas, obtained in CIA, were also used to study the ability o
During hypoglycaemia, counter-regulatory hormones are released, cognitive function is impaired and cerebral blood flow is increased. In the immediate period after normalisation of blood glucose only counter-regulatory hormones seem to be normalised. The aim of this study was to follow the changes in cerebral blood flow during a prolonged recovery period following moderate hypoglycaemia in normal m
Values of deltaC-13 obtained from conventional bulk sediment radiocarbon dates encompassing the Pleistocene-Holocene boundary have been compiled and plotted against C-14 age. In all, 286 lake sediment dates from southern Sweden in the range 8,000 to 13.000 BP have been evaluated. A significant decrease in deltaC-13 values, initiated shortly before 10,000 BP and amounting to 5 parts per thousand, i
In 1993 and 1994, the relation between breast size and hormonal factors and body constitution was studied in 65 healthy nulligravid women aged 19-25 years. Twenty-five women were current oral contraceptive users, 20 women were former users, and 20 women had never used oral contraceptives. Breast size was strongly positively correlated with current oral contraceptive use during menstrual cycle days
Although it is often assumed that birds strongly prefer tailwinds for their migratory flights, we predict that a strategy of no wind selectivity (traveling independently of winds) may be more favorable than wind selectivity (traveling on tailwind occasions but stopping to rest under headwind occasions) for birds with low energy costs of travel relative to rest and for birds that cannot use stopove
It is unclear how mutualistic relationships can be stable when partners disperse freely and have the possibility of forming associations with many alternative genotypes. Theory predicts that high symbiont relatedness should resolve this problem, but the mechanisms to enforce this have rarely been studied. We show that African fungus-growing termites propagate single variants of their Termitomyces
Soft tissue trauma is associated with platelet aggregation and sequestration in the lungs. This is believed to be an early step in the later development of adult respiratory distress syndrome. In the present experiment using a new method for in vivo dynamic studies of platelet sequestration, we wanted to evaluate the effect of soft tissue trauma on pulmonary platelet trapping in pigs and the influ
We measured the microvascular response to histamine in guinea pig skin. Histamine (40 mg ml-1) was given either as a skin prick test or applied topically onto a skin window. The skin window was prepared by applying suction and gentle warming to the skin so that a blister was formed, and by removing the top of the blister. The microvascular response was measured as the accumulation of radiolabelled
Insertions and deletions of entire codons have recently been discovered as a mechanism by which B cells, in addition to conventional base substitution, evolve the antibodies produced by their immunoglobulin genes. These events frequently seem to involve repetitive sequence motifs in the antibody-encoding genes, and it has been suggested that they occur through polymerase slippage. In order to bett
The wakes of two individual robins were measured in digital particle image velocimetry (DPIV) experiments conducted in the Lund wind tunnel. Wake measurements were compared with each other, and with previous studies in the same facility. There was no significant individual variation in any of the measured quantities. Qualitatively, the wake structure and its gradual variation with flight speed wer
Membrane type 1-matrix metalloprotease (MT1-MMP or MMP-14) is a major activator of pro-MMP-2 and is essential for skeletal development. We show here that it is required for branching morphogenesis of the submandibular gland but not the lung. Instead, in the lung, it is essential for postnatal development of alveolar septae. Lung development in Mmp14-/- mice is arrested at the prealveolar stage wit
