Canine lymphocyte cultures in vitro: Evaluation of peripheral blood lymphocyte response to mitogens

Lymphocytes from dog peripheral blood have been stimulated in vitro with 3 different mitogens (Con A, PHA and PWM). Culture medium was RPMI 1640 enriched with either autologous plasma, fetal calf serum or a newly described defined serum substitute. In such cultures the number of surviving and activated cells was measured by cytofluorometry and the proliferation was assessed by thymidine incorporation. In unstimulated cultures, up to 70% of all cells had disappeared (died) during the first 42 hours of incubation, whereas the number of viable cells was reduced to 50–60% in mitogen stimulated cultures. Of the surviving lymphocytes, between 25–40% of the cells appeared to have an elevated RNA-content (activated or G₁ cells). By comparison between thymidine incorporation and number of mitogen induced G₁ cells, a very high correlation was found (r=0.92). However, the slope of the regression line was much lower than expected. The low thymidine incorporation per activated cell was primarily related to the high cell death and a resulting dilution of tritiated thymidine. Indeed, preliminary results suggested that the same thymidine incorporation per G_1b cells could be obtained if peripheral blood lymphocytes were washed immediately before pulsing as could be obtained with lymphnode cells without washing.     

On the mode of action of the organophosphorus fungicide Hinosan

Samenvatting In onderzoek naar werkingsmechanismen van fungicide organische fosforverbindingen werd aangetoond dat Hinosan bijPiricularia oryzae tussenprodukten van de chitinesynthese kan doen ophopen. Dit duidt op een beïnvloeding van de chitinesynthese. De verbinding heeft ook een effect op de permeabiliteit van de celwandmembraan. Waarschijnlijk is dit effect primair verantwoordelijk voor de fungitoxiciteit van Hinosan en moet de remming van de chitinesynthese als een indirect effect worden beschouwd.     

Analysis of Mammalian Masticatory Mechanisms: Progress and Problems

Direct measurement of bone movements and muscle activation in mammalian mastication is now possible. Early results indicate that the patterns are quite variable and depart from the stereotyped versions sometimes reported. Most mammals masticate unilaterally; only a few chew simultaneously on both sides. Orbital movements are complex and three-dimensional. While most muscles are active during the reduction phase, it is difficult to define phases by sharp transitions of activity. The fascicles of pinnate muscles differ in fiber architecture and physiology; they tend to function at different times and with distinct mechanical advantages. Interspecific diversity and marked responses to food consistency and size, still preclude generalizations. Improved methods for comparisons among orbits, for correlation of forces and excursions, and automated correlations of movements, forces and electromyograms are beginning to be available and need to be more generallv applied to analysis.     

Breakdown of pisatin by some fungi pathogenic to Pisum sativum

Samenvatting Aan een voedingsmedium, geïnoculeerd met elk der schimmelsFusarium oxysporum f. sp.pisi ras 1,Mycosphaerella pinodes (pathogenen van de erwt),Cladosporium cucumerinum, Colletotrichum lindemuthianum enMonilinia fructigena (niet-pathogenen van de erwt) werd pisatine toegevoegd. Na incubatie gedurende een week werd het medium gecentrifugeerd. Zowel de bovenstaande vloeistof als het mycelium werd onderzocht op de aanwezigheid van pisatine. Uit de U.V.-absorptiespectra van de vloeistof en alcoholextracten van het mycelium blijkt, dat beide pathogenen het pisatine kunnen afbreken, maar de drie niet-pathogenen niet.