Identification and design of a novel series of MGAT2 inhibitors

[Acyl CoA]monoacylglycerol acyltransferase 2 (MGAT2) is of interest as a target for therapeutic treatment of diabetes, obesity and other diseases which together constitute the metabolic syndrome. In this Letter we report our discovery and optimisation of a novel series of MGAT2 inhibitors. The development of the SAR of the series and a detailed discussion around some key parameters monitored and addressed during the lead generation phase will be given. The in vivo results from an oral lipid tolerance test (OLTT) using the MGAT2 inhibitor (S)-10, shows a significant reduction (68% inhibition relative to na?ve, p <0.01) in plasma triacylglycerol (TAG) concentration.     

Chydorus arcticus n.sp., a new cladoceran crustacean (Chydoridae: Chydorinae) from the North Atlantic arctic and Subarctic areas

Chydorus arcticus n.sp. (Cladocera: Chydoridae: Chydorinae) is described, figured, and differentiated from the closely relatedC. sphaericus (O.F. Müller, 1785). The known distribution of the species is given, and some aspects of speciation of arctic crustaceans are pointed out.     

Algesia and local responses induced by neurokinin A and substance P in human skin and temporal muscle

Neurokinin A (NKA), substance P (SP) and the two peptides combined (SP + NKA) were injected intracutaneously on the forearm and into the temporal muscle of healthy volunteers. Pain intensity, cutaneous wheal and flare responses and tenderness of the temporal muscle were quantitated. SP but not NKA induced cutaneous pain. This relates the algesic effect of SP to the specific N-terminal amino acid sequence of the peptide, not shared by NKA. NKA, however, potentiated the algesic effect of SP as SP + NKA induced a significantly prolonged cutaneous pain sensation. Both peptides induced wheals, but only SP induced flare. These results confirm previous studies relating wheal formation to the identical C-terminal amino acid sequence of the two peptides and flare reaction to the N-terminal part of SP. Injections into the temporal muscle did not cause pain or tenderness.     

Filtration rate capacities in 6 species of European freshwater bivalves

Summary Filtration rate capacities in undisturbed freshwater bivalves were determined by means of two different methods (indirect clearance and suction methods) in Anodonta anatina (L.), Unio tumidus Philipsson, Unio pictorum (L.), Unio crassus Philipsson, Dreissena polymorpha (Pallas) and Sphaerium corneum (L.). In A. anatina, D. polymorpha, and S. corneum the filtration rate (FR, 1 h^-1) at 19–20°C as a function of dry tissue weight (DW, g) or ash-free dry weight (AFDW, g) could be expressed by the equations: 1.10 DW^0.78, 6.82 DW^0.88, and 2.14 AFDW^0.92, respectively. In U. tumidus, U. pictorum, and U. crassus filtration rates were comparable with those of A. anatina. In D. polymorpha the b value of the corresponding regression of gill area on dry weight was 0.87. The rates of water transport in freshwater bivalves are 2–8 times lower than in marine bivalves of comparable size. A corresponding difference in the filtration rate per gill area unit is found. The measured filtration rates in undisturbed bivalves are substantially higher (at least 4 times) than previously reported. This indicates that the impact of bivalve water processing on freshwater ecosystems is greater than hitherto suggested.     

Cutting and closing without recombination in V(D)J joining.

Open and shut junctions are rare (V(D)J joining products in which site-specific recognition, cleavage and re-ligation of joining signals has been uncoupled from recombination. Here, we investigate the relationship of opening and shutting to recombination in two ways. First, we have tested a series of substrates containing one or two joining signals in an in vivo assay. Opening and shutting can be readily observed in substrates that have only one consensus joining signal. Thus, unlike recombination, the majority of open and shut events do not require interactions between two canonical joining signals. Next we examined two-signal substrates to investigate the effect of signal proximity on the frequency of dual open and shut events. These experiments indicate that at least some of the time opening and shutting can be a two-signal transaction. Together these results point to two mechanistically related, but distinct origins for open and shut joining events. In one case, cutting and closing may occur without interaction between two signals. In the other, we suggest that interaction of a canonical signal with 'cryptic' signal-like elements whose sequence is extensively diverged from canonical signals, may bias the V(D)J recombination machinery towards opening and shutting rather than recombination. Open and shut operations could in this way provide a means whereby mistakes in target recognition by the V(D)J recombination machinery produce a non-recombinant outcome, avoiding deleterious chromosomal rearrangements in lymphoid tissues.     

Effects of antimalarial drugs on phospholipase A and lysophospholipase activities in plasma membrane, mitochondrial, microsomal and cytosolic subcellular fractions of rat liver

Activities of membrane-associated phospholipases A1 and A2, and membrane-associated as well as soluble lysophospholipases were measured in different subcellular fractions of rat liver, using suspensions of stereospecifically labelled radioactive phospholipids as substrates. Plasma membranes and endoplasmic reticulum were shown to contain phospholipase A1 and lysophospholipase activities, both of which could be stimulated by Ca2+, mitochondria Ca2+-dependent phospholipase A2 and cytosol Ca2+-independent lysophospholipase activities. Each of these lipolytic enzymes could be inhibited by antimalarial drugs (chloroquine, mepacrine, primaquine) at concentrations above 1 x 10(-4) M. Inhibition of the alkaline cytosolic lysophospholipase by these drugs was noncompetitive with respect to the substrate, and the inhibitory potency increased, when the pH was raised.     

Proteins of the Brain Extracellular Fluid: Evidence for Release of S-100 Protein

Abstract: Extracellular protein fractions were obtained (1) by mild, isotonic irrigation of freshly perfused brain tissue; (2) by collection of proteins released into super-fusing medium by physiologically viable slices of rat hippocampus; and (3) by sampling the CSF of anesthetized rats. Analysis of the S-100 protein content of these fractions gave values of 2.8, 4.2, and 1.8 μg S-100/mg protein, respectively. These values were three- to sixfold higher than the S-100 content of the soluble cytoplasmic protein fractions from the same tissue. This several-fold higher S-100 content of the extracellular protein fractions relative to the intracellular cytoplasmic protein fractions indicates that S-100 is selectively released into the extracellular spaces of the brain. We suggest that the biological function of this CNS protein may involve intercellular transfer.     

The Ca2+ permeability of sarcoplasmic reticulum vesicles II. Ca2+ efflux in the energized state of the calcium pump

Ca²⁺ efflux from sarcoplasmic reticulum vesicles was studied by measurements of net Ca²⁺ uptake, ⁴⁵Ca²⁺ flux and hydrolysis of energy-rich phosphate. The maximal Ca²⁺ uptake capacity (150–200 nmol/mg protein at pH 6.7, 10 mM MgCl₂ and μ=0.26) was independent of the nature and concentration of the energy-donating substrate (ATP or carbamyl phosphate) and of temperature (15–35°C), suggesting coupling between influx and efflux of Ca²⁺. In the presence of high concentrations of ATP, this efflux of Ca²⁺ was much higher than the passive Ca²⁺ permeation, measured after ATP or Ca²⁺ depletion of the reaction medium. Ca²⁺ efflux was imperceptible at vesicle filling levels below 35–40 nmol Ca²⁺/mg protein, and uncorrelated to the inhibition of the Ca²⁺-ATPase by high intravesicular Ca²⁺ concentrations. Analysis of the data indicated that Ca²⁺ efflux under our conditions probably is associated with one of the Ca²⁺-ATPase partial reactions occurring after dephosphorylation, rather than with a reversal of the Ca²⁺ translocation step in the phosphorylated state of the enzyme. Furthermore, passive Ca²⁺ permeation may be concurrently reduced during the enzymatically active state. It is proposed that both Ca²⁺ efflux and passive Ca²⁺ permeation (Ca²⁺ outflow) proceed via the same channels which are closed (occluded) during part of the Ca²⁺-ATPase reaction cycle.     

Cytologische Untersuchungen an Nematodengallen

Zusammenfassung Zwei verschiedene Faktoren bewirken die Vergrößerung der Riesenzellen (RZ) in den Gallen des NematodenMeloidogyne arenaria (auf Kakteen und anderen Wirten): die Hypertrophie der wachsenden RZ und die Syncytienbildung (Auflösung trennender Zellwände und Verschmelzung kleinerer Zellen).Parallel mit der Entwicklung des Parasiten durchlaufen die RZ und ihre Kerne vier verschiedene Entwicklungsstadien; währenddessen verändern diese Kerne auf charakteristische Weise ihre Größe, Struktur und Gestalt, parallel damit erhöht sich der Polyploidiegrad (die Charakteristika der einzelnen Stadien sind vom jeweiligen Wirt weitgehend unabhängig): der Umriß wandelt sich vorerst durch starke physiologische Beanspruchung des Kerns, in späteren Stadien durch davon unabhängige Mitosestörungen bzw. durch Spindel- und Plattenverschmelzungen während der synchronen Teilungen in den RZ (bei der CrassulaceeCotyledon treten Mikronuklei auf). Die beiden letztgenannten Vorgänge verursachen die Polyploidisierung sowohl in den RZ als auch in manchen unmittelbar an die RZ anschließenden parenchymatischen Zellen, während das übrige Gewebe weitgehend unbeeinflußt bleibt.Eng mit den genannten Ursachen hängt die sehr variable Zahl der Kerne pro RZ und ihre Struktur zusammen: im Stadium der größten physiologischen Beanspruchung der RZ ist der Kern sehr wolkig, später sind die Chromozentren sehr kompakt. Unabhängig vom jeweiligen Entwicklungsstadium der RZ ist das Chromatin an der Peripherie des Kerns konzentriert. Durch die Ursachen, die zu Polyploidisierung und variablem Umriß führen, kommt es zu wahrscheinlich plasmatischen Einfaltungen und Einschlüssen innerhalb des Kerns.Nicht nur im Gallen-, sondern auch im unbeeinflußten Gewebe zeigen Kerne ab einer bestimmten Größe bzw. eines bestimmten Polyploidiegrades stärker lichtbrechende, nicht oder nur wenig anfärbbare, in ihrer Größe zwar vom Kernvolumen abhängige, doch trotzdem kleine Kugeln (in kleineren Kernen sind sie wahrscheinlich nur wegen ihrer Kleinheit nicht auffindbar). Sie sind nur in Glutaraldehyd-fixiertem Material sichtbar, AE als Fixierungsmittel löst sie auf. Sie befinden sich oft in unmittelbarer Umgebung des Nukleolus und hängen wahrscheinlich ursächlich mit ihm zusammen, aber eine exakte Analyse kann nicht gegeben werden.

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Summary Two determining factors induce the enlargement of giant cells in galls caused by the root-knot nematode (Meloidogyne arenaria in roots of some Cactaceae and other hosts): hypertrophy of the growing giant cells and formation of syncytia.Corresponding with the evolution of the parasitic larva the giant cells and their nuclei become altered through four different stages; the nuclei change their volume, structure, shape and their degree of polyploidy, independent of the specific host: the contour of the nuclei is altered during the development of the giant cells first by physiological factors, on the other hand — later on — by mitotic inhibition resp. by fusing mitotic spindles or mitotic figures during synchronous mitotic divisions in the giant cells (micronuclei occur inCotyledon, Crassulaceae). Polyploidization is induced by the last two mentioned factors in giant cells as well as in some parenchymatous cells surrounding giant cells.Conditioned by these mentioned factors the number of nuclei per giant cell, their structure and shape are very variable. All nuclei in the giant cells possess a significant feature: accumulation of the chromatin material at the nuclear periphery, while the centre of the nucleus is almost optically empty. This structure occurs also during the stage with the greatest physiological stress. Plasmatical foldings and inclusions occur in some voluminous nuclei, produced by the factors leading to polyploidy resp. to variable shape.Not only in giant cells, but also in normal tissues — if their nuclei have reached a low degree of polyploidy — small, refractioning, poor stainable globules exist (they cannot be seen in small nuclei, probably they are too small): they are often sitting upon the nucleolus and are surely corresponding with him, their exact constitution and origin is unknown. They can only be seen in Glutaraldehyd-fixed material, in acetic-alcohol-fixation they are dissolved.