Reference

A spot test with toluidine blue for allophane and imogolite

A spot test with toluidine blue for allophane and imogolite. Wada, Koji; Kakuto, Yasuko (Fac. Agric., Kyushu Univ., Fukuoka 812, Japan). Soil Sci. Soc. Am. J., 49(1), 276-8 (English) 1985. CODEN: SSSJD4. ISSN: 0361-5995. DOCUMENT TYPE: Journal CA Section: 19 (Fertilizers, Soils, and Plant Nutrition) Section cross-reference(s): 79 Toluidine blue (I) [92-31-9] is adsorbed on neg. charged colloids and exhibits a characteristic color change from blue to purplish red (metachromasis). A procedure to test for metachromasis of I was developed and tested on Chile and Ecuador soil samples contg. and not contg. allophane [12172-71-3] and imogolite [12263-43-3]. A soil sample/0.02% aq. I soln. ratio of 30-50 mg/0.4 mL was adopted. Metachromasis did not occur for any sample contg. both allophane and imogolite or in 10 samples contg. only allophane, but did occur in 9 samples contg. acid oxalate-sol. aluminosilicates. Thus, the absence of the metachromasis can be used as a test for allophane and imogolite, though it is not specific but is rather a test for the absence or near-absence of neg. charge sites in the soil, or for neg. charge sites with no access to a large org. cation. Though further tests are required, when used along with the pH in NaF or the acid oxalate-extractable Al, the toluidine blue test can provide key information on soil-forming processes in volcanic ash and is useful for classification of Andepts and related soils.

Intracellular parasite killing induced by electron carriers

Intracellular parasite killing induced by electron carriers. II. Correlation between parasite killing and the induction of oxidative events in macrophages. Mauel, Jacques; Schnyder, Joerg; Baggiolini, Marco (Inst. Biochem., WHO Immunol. Res. Train. Cent., Epalinges CH-1066, UK). Mol. Biochem. Parasitol., 13(1), 97-110 (English) 1984. CODEN: MBIPDP. ISSN: 0166-6851. DOCUMENT TYPE: Journal CA Section: 1 (Pharmacology) Mouse peritoneal macrophages infected with Leishmania parasites were exposed in vitro to the electron carriers methylene blue (MB) [61-73-4], toluidine blue 0 (TB) [92-31-9], phenazine methosulfate (PMS) [299-11-6] and crystal violet (CV) [548-62-9]. This led to parasite destruction without harm to the macrophages. The kinetics of intracellular killing depended on both the drug concn. and the duration of exposure; over 80% of the microorganisms were inactivated within 2.5 min of incubation of the parasitized cells with 10-4 M MB. On a molar basis, the drugs were considerably more active against intracellular compared to free parasites, suggesting that the macrophages themselves play a role in the obsd. anti-parasite toxicity. Intracellular killing by macrophages exposed to MB, TB, and PMS correlated with the stimulation of O uptake and hexose monophosphate shunt activity in the cells. Cytochrome c markedly inhibited MB-induced intracellular parasite destruction as well as completely blocking parasite killing in macrophages activated by lymphokines, pointing to O2-, H2O2 or products derived therefrom as possible mediators of macrophage toxic activity in both instances. Cytochrome c did not protect free parasites from the direct toxicity of the drug, however. Lipopolysaccharide promoted parasite destruction by lymphokine-activated macrophages, but failed to do so for electron carrier-stimulated cells. It appears that intracellular killing induced by electron carriers results from a direct interaction of the drugs with cellular redox systems, leading to the generation of O metabolites toxic for the parasites.