Long term toxicity studies with endotoxoid in monkeys

Zusammenfassung Vor dem Hintergrund der vielfältigen Endotoxoidwirkung wurde diese Substanz in chronischen Toxizitätsstudien beiMacaca mulatta geprüft. Endotoxoid wurdeMacaca mulatta in einer Dosierung von jeweils 100/kg in insgesamt 51 Injektionen innerhalb von 12 Wochen injiziert. Dabei zeigte sich, dass diese Substanz keinen Einfluss auf die geprüften klinischchemischen Parameter hatte und bei makroskopischer und histologischer Untersuchung keine Veränderungen auftraten.

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Kindly supported by a grant from the Deutsche Forschungsgemeinschaft to Dr.Fritsch.     

The influence of deoxycorticosterone,digitoxigenin and cyanide ions on the respiration ofFusarium lini (Bolley)

Zusammenfassung Die Atmung von wachsenden Kulturen vonFusarium lini (Bolley) wird durch Cortexon und Digitoxigenin während ihrer Hydroxylierung erhöht. 0,001-molares Kaliumcyanid, allein und in Gegenwart von Cortexon und Digitoxigenin, bewirkt ebenfalls eine Erhöhung des Sauerstoffverbrauchs. In kleineren und grösseren Konzentrationen hingegen hemmt Kaliumcyanid die Atmung. Die vom Mikroorganismus aufgenommene Sauerstoffmenge nimmt mit dessen Wachstum ab.

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Reactions with Micro-organisms. Part. 20².     

Bose-Einstein condensation of the triplet states in the magnetic insulator TlCuCl3

Bose-Einstein condensation denotes the formation of a collective quantum ground state of identical particles with integer spin or intrinsic angular momentum. In magnetic insulators, the magnetic properties are due to the unpaired shell electrons that have half-integer spin. However, in some such compounds (KCuCl3 and TlCuCl3), two Cu2+ ions are antiferromagnetically coupled to form a dimer in a crystalline network: the dimer ground state is a spin singlet (total spin zero), separated by an energy gap from the excited triplet state (total spin one). In these dimer compounds, Bose-Einstein condensation becomes theoretically possible. At a critical external magnetic field, the energy of one of the Zeeman split triplet components (a type of boson) intersects the ground-state singlet, resulting in long-range magnetic order; this transition represents a quantum critical point at which Bose-Einstein condensation occurs. Here we report an experimental investigation of the excitation spectrum in such a field-induced magnetically ordered state, using inelastic neutron scattering measurements of TlCuCl3 single crystals. We verify unambiguously the theoretically predicted gapless Goldstone mode characteristic of the Bose-Einstein condensation of the triplet states.     

ISSR markers based on GA and AG repeats reveal genetic relationship among rice varieties tolerant to drought, flood, or salinity

Drought, flood, salinity, or a combination of these limits rice production. Several rice varieties are well known for their tolerance to specific abiotic stresses. We determined genetic relationship among 12 rice varieties including 9 tolerant to drought, flood, or salinity using inter-simple sequence repeat (ISSR) markers. Based on all markers, the nine tolerant varieties formed one cluster distinct from the cluster of three control varieties. The salt-tolerant varieties were closest to two flood-tolerant varieties, and together they were distinct from the drought-tolerant varieties. (GA)₈YG was the most informative primer, showing the highest polymorphic information content (PIC) and resolving power (Rp). The drought-, flood-, and salt-tolerant varieties grouped in three distinct clusters within the group of tolerant varieties, when (GA)₈YG was used. Sabita was the only exception. The two aus varieties, Nagina22 and FR13A, were separated and grouped with the drought- and flood-tolerant varieties, respectively, but they were together in dendrograms based on other primers. The results show that ISSR markers associated with (GA)₈YG delineated the three groups of stress-tolerant varieties from each other and can be used to identify genes/new alleles associated with the three abiotic stresses in rice germplasm.     

Netrin-1-mediated axon outgrowth and cAMP production requires interaction with adenosine A2b receptor

The netrins, a family of laminin-related secreted proteins, are critical in controlling axon elongation and pathfinding. The DCC (for deleted in colorectal cancer) protein was proposed as a receptor for netrin-1 in the light of many observations including the inhibition of netrin-1-mediated axon outgrowth and attraction in the presence of an anti-DCC antiserum, the similitude of nervous system defects in DCC and netrin-1 knockout mice and the results of receptor swapping experiments. Previous studies have failed to show a direct interaction of DCC with netrin-1 (ref. 10), suggesting the possibility of an additional receptor or co-receptor. Here we show that DCC interacts with the membrane-associated adenosine A2b receptor, a G-protein-coupled receptor that induces cAMP accumulation on binding adenosine. We show that A2b is actually a netrin-1 receptor and induces cAMP accumulation on binding netrin-1. Finally, we show that netrin-1-dependent outgrowth of dorsal spinal cord axons directly involves A2b. Together our results indicate that the growth-promoting function of netrin-1 may require a receptor complex containing DCC and A2b.     

Pyrrolizidine alkaloids fromSymphytum officinale L. and their percutaneous absorption in rats

Summary An analysis of a commercial sample of Symphyti radix originating from Poland with a total alkaloid content of 0.07% revealed the presence of 7 pyrrolizidine alkaloid-N-oxides: 7-acetyl intermedine, 7-acetyl lycopsamine as the main constituents and lycopsamine, intermedine, symphytine and traces of 2 further not yet identified alkaloids. The percutaneous absorption of these alkaloids was investigated in rats, using a crude alcoholic extract of the plant corresponding to a dose of 194 mg alkaloid-N-oxides/kg b.wt. The excretion of N-oxides in the urine during 2 days was in the range of 0.1–0.4% of the dose. The dermally absorbed N-oxides are not or only to a small extent converted to the free alkaloids in the organism. The oral application led to a 20–50 times higher excretion of N-oxides and free alkaloids in the urine.We thank Dr C. C.J. Culvenor, Parkville, Australia, for providing authentic samples of 7-acetylintermedine, 7-acetyllycopsamine and echimidine, and B. Karlhuber, Finnigan, Basle, for the GC-MS analysis.     

Calcifying bacteria and carbonic anhydrase]

Carbonic anhydrase activity was measured on bacteria known for their calcifying power. The results obtained allow us to conclude that carbonic anhydrase is not present in their enzymatic equipment. Nevertheless, the addition of carbonic anhydrase in culture media increases the growth of the cultures and their calcifying power. This result is due to the direct action of the enzyme on the pH of the culture medium. The results obtained could be applied to the mechanism of dental plaque calcification.