Comparative effects of dopamine and dobutamine on glucoregulation in a rat model.

The influence of dopamine as compared with dobutamine on glucose homeostasis has been assessed in thyroidectomized euthyroid rats. Both sympathomimetic agents were given intravenously over 6 h at four dosages, varying from 2 to 30 micrograms.kg-1.min-1. Immediately before the end of the infusion period, serum concentrations of glucose and insulin as well as plasma glucagon concentrations were measured. Dobutamine infusions did not exert any influence on these parameters. At a dose of 7.5 micrograms.kg-1.min-1, dopamine infusion caused a decrease in glucose concentrations, accompanied by a rise of glucagon and insulin levels. Glucose levels were significantly increased in the presence of unaltered insulin and decreasing glucagon levels at higher dopamine doses. The rise in glucose levels was reversed by 8 micrograms.kg-1.min-1 and inverted to a decrease by 12 micrograms.kg-1.min-1 of the alpha-adrenergic blocking agent phentolamine, simultaneously infused with 15 micrograms.kg-1.min-1 dopamine, while the insulin levels were increased and glucagon levels remained elevated. These findings demonstrate that dopamine acts on glucoregulation divergently, according to the dosage applied. The data suggest that dopamine rather than dobutamine treatment may disturb glucose homeostasis.     

Synthesis and mass spectra of 4-O-acetyl-1,5-anhydro-2,3,6-tri-O -(methoxycarbonylmethyl)-D-glucitol and the positional isomers of 4- O-acetyl-1,5-anhydro-di-O-(methoxycarbonylmethyl)-O-methyl-D-glucitol and 4-O-acetyl-1,5-anhydro-O-(methoxycarbonylmethyl)-di-O-methyl-D-glucitol .

Reductive cleavage of fully methylated, partially O-carboxymethylated cellulose had previously been shown to produce 4-O-acetyl-1,5-anhydro-2,3,6-tri-O-methyl-, -2-O-(methoxycarbonylmethyl)-3,6-di-O-methyl-, -3-O-(methoxycarbonylmethyl)-2,6-di-O-methyl-, -6-O-(methoxycarbonylmethyl)-2,3-di-O-methyl-, -2,3-di-O-(methoxycarbonylmethyl)-6-O-methyl-, -2,6-di-O-(methoxycarbonylmethyl)-3-O-methyl-, -3,6-di-O-(methoxycarbonylmethyl)-2-O-methyl-, and -2,3,6-tri-O-(methoxycarbonylmethyl)-D-glucitol. Described herein is the independent synthesis of these derivatives, except for the first, which had been reported. In addition, their 1H-n.m.r. spectra, chemical-ionization (NH3) mass spectra, and electronionization mass spectra are tabulated.     

Molecular identification of powdery mildew resistance genes in common wheat (Triticum aestivum L.)

RFLP markers for the wheat powdery mildew resistance genes Pm1 and Pm2 were tagged by means of near-isogenic lines. The probe Whs178 is located 3 cM from the Pm1 gene. For the powdery mildew resistance gene Pm2, two markers were identified. The linkage between the Pm2 resistance locus and one of these two probes was estimated to be 3 cM with a F₂ population. Both markers can be used to detect the presence of the corresponding resistance gene in commercial cultivars. Bulked segregant analysis was applied to identify linkage disequillibrium between the resistance gene Pm18 and the abovementioned marker, which was linked to this locus at a distance of 4 cM. Furthermore, the RAPD marker OPH-11₁₉₀₀ (5-CTTCCGCAGT-3) was selected with pools created from a population segregating for the resistance of Trigo BR 34. The RAPD marker was mapped about 13 cM from this resistance locus.     

Red-listed lichens in Sweden: habitats, threats, protection, and indicator value in boreal coniferous forests

The three major threats to lichens in Sweden; forestry, air pollution, and structural changes in the agricultural landscape, are outlined. Forestry is the most serious. The majority of the red-listed lichens in forests are found in productive forests with a continuity in tree growth, but nearly 70% of the protected area in Sweden consists of alpine landscapes. Examples of important habitats with red-listed lichens are described, e.g. Alnus glutinosa marshes, alvar-vegetation, broad-leaved deciduous forests and different Picea abies forests. The use of selected indicator species of lichens and macrofungi (mainly red-listed species) in boreal coniferous forests provides information on continuity in tree growth of an area, and on earlier influences of forestry. Examples of indicator species for different types of forest are presented and discussed. In spite of the Swedish right of common accesso, collecting of lichens is forbidden without permission from the land-owner. Collecting in protected areas is allowed only with a permit obtained from the authorities.     

Fixation of neural tissue for electron microscopy with an electronically controlled perfusion pump

Many attempts to improve the perfusion of mammalian tissues aim at changes of the osmotic pressure. We describe a method for fixation of nervous tissues controlling both the hydrostatic pressure and the flow rate of a perfusion solution. The constancy of these parameters is guaranteed by an electronically controlled perfusion pump. Thus, a more uniform and complete preservation can be achieved. Further advantages of this method include provision for a rapid succession of rinsing and fixation solution and a continuous control of the hydrostatic pressure during perfusion.     

Genetic analysis of the H-2D region using a new intra-D-region recombinant mouse strain

A rare D-region recombination event which gave rise to the B10.RQDB major histocompatibility complex haplotype has been examined to ascertain the nature of the crossover and to determine which class I genes are present in the new alignment of D-region genes. Serologic analysis have shown that the B10 . RQDB major histocompatibility complex recombinant mouse inherited the H-2Dd gene from the B10.T(6R) parental line and the H-2Db gene from the B10.A(2R) parental line, representing the first example of an intra-D-region crossover resulting from an intercross. Previous molecular genetic analyses of the d and b haplotypes revealed structural diversity in the organization of their D-region gene clusters. Hence, the D region is comprised of five class I genes in the d haplotype and only one in the b haplotype. Because allelic relationships among the various D-region genes are not defined, either a homologous or nonhomologous alignment of genes has generated the RQDB crossover. Therefore, the possibility that all three D-region antigen-presenting molecules (Dd, Ld, and Db) might be encoded by the RQDB haplotype was examined. Fluorescence-activated cell sorter and cytotoxic T lymphocyte analyses revealed no detectable levels of H-2Ld cell-surface expression, confirming earlier studies with antibody-mediated cytotoxicity and immunoprecipitation. Southern blot analysis localized the recombination point to within a 1-kb region at the centromeric end of the H-2Ld gene on the B10 . T(6R) chromosome in a region of high homology to the H-2Db gene on the B10 . A(2R) chromosome. Together, these studies define the D region of the RQDB haplotype as containing the five class I genes: Dd, D2d, D3d, D4d, and Db. In addition to providing insight into rare recombination events in the D region, the B10.RQDB mouse should be a useful tool for exploring the function of D-region genes.