Iron porphyrin treatment extends survival in a transgenic animal model of amyotrophic lateral sclerosis

Oxidative damage, produced by mutant Cu/Zn superoxide dismutase (SOD1), may play a role in the pathogenesis of amyotrophic lateral sclerosis (ALS), a devastating motor neuron degenerative disease. A novel approach to antioxidant therapy is the use of metalloporphyrins that catalytically scavenge a wide range of reactive oxygen and reactive nitrogen species. In this study, we examined the therapeutic potential of iron porphyrin (FeTCPP) in the G93A mutant SOD1 transgenic mouse model of ALS. We found that intraperitoneal injection of FeTCPP significantly improved motor function and extended survival in G93A mice. Similar results were seen with a second group of mice wherein treatment with FeTCPP was initiated at the onset of hindlimb weakness-roughly equivalent to the time at which treatment would begin in human patients. FeTCPP-treated mice also showed a significant reduction in levels of malondialdehyde (a marker of lipid peroxidation), in total content of protein carbonyls (a marker of protein oxidation), and increased neuronal survival in the spinal cord. These results therefore provide further evidence of oxidative damage in a mouse model of ALS, and suggest that FeTCPP could be beneficial for the treatment of ALS patients.     

Ester synthesis in an aqueous environment by<Emphasis Type="Italic"> Streptococcus thermophilus</Emphasis> and other dairy lactic acid bacteria

The ability of Streptococcus thermophilus ST1 and 19 other dairy lactic acid bacteria (LAB) to synthesize esters was investigated in an aqueous environment. These LAB were able to synthesize esters from alcohols and glycerides via a transferase reaction (alcoholysis) in which fatty acyl groups from glycerides were transferred to alcohols. S. thermophilus ST1 was active on tributyrin and on di- or monoglycerides of up to C10 with ethanol as the acyl acceptor. This strain was also active on a diglyceride of C6 and monoglyceride of C8 with 2-phenyl ethanol as the acyl acceptor. Alcoholysis occurred preferentially over hydrolysis. S. thermophilus ST1 had an apparent K_m value of 250 mM for ethanol and an apparent K_m value of 1.3 mM for tributyrin, measured against whole cells. Around 80% of both the transferase activity and the esterase activity were detected in the cell-free extract (CFE) of strain ST1. Both activities in the CFEs of five LAB tested were, to a similar degree, enhanced slightly by growth in the presence of ethanol and tributyrin. Using tributyrin and ethanol as substrates, the transferase activities ranged over 0.006–1.37 units/mg cell dry weight among the LAB tested and were both species- and strain-dependent.     

Liposome-delivered superoxide dismutase prevents nitric oxide-dependent motor neuron death induced by trophic factor withdrawal

Inhibition of nitric oxide synthesis prevents rat embryonic motor neurons from undergoing apoptosis when initially cultured without brain-derived neurotrophic factor. Using an improved cell culture medium, we found that the partial withdrawal of trophic support even weeks after motor neurons had differentiated into a mature phenotype still induced apoptosis through a process dependent upon nitric oxide. However, nitric oxide itself was not directly toxic to motor neurons. To investigate whether intracellular superoxide contributed to nitric oxide-dependent apoptosis, we developed a novel method using pH-sensitive liposomes to deliver Cu, Zn superoxide dismutase intracellularly into motor neurons. Intracellular superoxide dismutase prevented motor neuron apoptosis from trophic factor withdrawal, whereas empty liposomes, inactivated superoxide dismutase in liposomes or extracellular superoxide dismutase did not. Neither hydrogen peroxide nor nitrite added separately or in combination affected motor neuron survival. Our results suggest that a partial reduction in trophic support induced motor neuron apoptosis by a process requiring the endogenous production of both nitric oxide and superoxide, irrespective of the extent of motor neuron maturation in culture.     

DNA recognition by quinoline antibiotics: use of base-modified DNA molecules to investigate determinants of sequence-specific binding of luzopeptin

The luzopeptin antibiotics contain a cyclic decadepsipeptide to which are attached two quinoline chromophores that bisintercalate into DNA. Although they bind DNA less tightly than the structurally related quinoxaline antibiotics echinomycin and triostin A, the molecular basis of their interaction remains unclear. We have used the PCR in conjunction with novel nucleotides to create specifically modified DNA for footprinting experiments. In order to study the influence that removal, addition or relocation of the guanine 2-amino group, which normally identifies G.C base pairs from the minor groove, has on the interaction of luzopeptin antibiotics with DNA. The presence of a purine 2-amino group is not strictly required for binding of luzopeptin to DNA, but the exact location of this group can alter the position of preferred drug binding sites. It is, however, not the sole determinant of nucleotide sequence recognition in luzopeptin-DNA interaction. Nor can the selectivity of luzopeptin be attributed to the quinoline chromophores, suggesting that an analogue mode of DNA recognition may be operative. This is in contrast to the digital readout that seems to predominate with the quinoxaline antibiotics.     

Volatile Organic Compounds Associated with Microbial Growth in Automobile Air Conditioning Systems

Volatile organic compounds from Penicillium viridicatum and Methylobacterium mesophilicum growing on laboratory media and on component materials of automobile air conditioners were analyzed with gas chromatography and mass spectrometry. P. viridicatum produced compounds such as 4-methyl thiazole, terpenes and alcohols, whereas M. mesophilicum produced dimethyl disulfide, dimethyl trisulfide, and chlorophenol with growth on laboratory media. In comparison with laboratory media, fewer volatiles were detected from colonized foam insulation materials. Biofilms of M. mesophilicum on aluminum evaporator components produced mainly dimethyl disulfide. These biofilms, after inoculation with P. viridicatum, produced offensive smelling alcohols and esters such as 2-methyl propanol, 3-penten-2-ol, and the ethyl ester of butanoic acid. The moisture and substrates innate to the automobile air conditioning systems provided an environment suitable for microbial biofilm development and odor production. Reduction of retained moisture in the air conditioning system coupled with use of less susceptible or antimicrobial substrates are advised for remediation of the noxious odors. Received: 26 February 2000 / Accepted: 2 May 2000