14'-Hydroxymytoxin B and 16-hydroxyroridin E,two new cytotoxic trichothecenes from Myrothecium roridum

Two new trichothecenes, 14'-hydroxymytoxin B (1) and 16-hydroxyroridin E (3), were isolated from a fermentation extract of Myrothecium roridum. The structures of 1 and 3 were determined by spectral data interpretation. Both compounds showed potent cytotoxic activity against primary soft-tissue sarcoma cells.     

Comparing dual-stream and standard cardiopulmonary bypass in pigs

BACKGROUND: Dual-stream (DS) and standard cardiopulmonary bypass (CPB) were compared. METHODS: A DS catheter inserted into the distal ascending aorta across the arch pumps blood through an upper lumen (maximum 2.25 L/min) directed by a bloodstreaming baffle toward the arch vessels. A separate lower lumen pumps blood (maximum 3.75 L/min) into the aorta caudad to the inflated baffle. The baffle is flat and horizontal along the catheter. When the baffle is collapsed the heart or both lumens may perfuse all organs. For 30 minutes 8 randomized CPB pigs had corporeal cooling to 32 degrees C and for 30 minutes had rewarming to 36 degrees C. Eight randomized DS pigs had 25 degrees C upper lumen cooling for 60 minutes. Lower lumen blood flow was streamed at 32 degrees C for 30 minutes, then rewarmed to 36 degrees C for 30 minutes. RESULTS: The change in relative lower lumen to brain blood flow as determined by brain-counted microspheres (15 micron) injected into the ascending aorta was less for DS brains than controls during full flow (DS 63.4+/-129.5 versus CPB 2,585.4+/-250.8, p < 0.001), and when injected into the ejecting-heart left atrium just after weaning off only lower lumen blood flow (DS 250.8+/-297.3 versus CPB 1,159.1+/-782.3, p < 0.001). DS brain temperatures were lower at an equal pump-off core temperature of 36 degrees C+/-0.5 degrees C (DS 31.6 degrees C+/-3.2 degrees C versus CPB 36.5 degrees C+/-1.7 degrees C, p < 0.025). Jugular O2 saturations were not different. CONCLUSIONS: DS-CPB prioritizes pump-filtered separate cold blood flow to the brain over a blood-streaming baffle to wash away potentially surgery related air and particulate matter arising from the heart or ascending aorta.     

Fluorescent zinc indicators for neurobiology

Mounting evidence indicates that zinc has multiple roles in cell biology, viz. as a part of metalloenzyme catalytic sites, as a structural component of gene regulatory proteins, and (like calcium) as a free signal ion, particularly in the cortex of the brain. While most Zn(II) in the brain is tightly bound, such that free Zn(II) levels extracellularly and intracellularly are likely to be picomolar, a subset of glutamatergic neurons possess weakly bound zinc in presynaptic boutons which is released at micromolar levels in response to a variety of stimuli. Key to further progress in understanding the multiple roles of zinc will be the availability of fluorescent indicator systems that will permit quantitative determination and imaging of zinc fluxes and levels over a broad concentration range both intracellularly and extracellularly using fluorescence microscopy. Towards that end, we have compared a variety of fluorescent indicators for their sensitivity to Zn(II) and Cu(II), selectivity for Zn(II) in the presence of potential interferents such as Ca(II) or Mg(II), and potential for quantitative imaging. The commercially available probes Fura-2, Mag-Fura-5, Newport Green DCF, and FuraZin-1 were compared with the carbonic anhydrase-based indicator systems for selectivity and sensitivity. In addition, intracellular levels of Zn following excitotoxic insult were determined by single pixel fluorescence lifetime microscopy of Newport Green DCF, and extracellular levels of free zinc following stimulus of rat hippocampal slices were determined ratiometrically with a carbonic anhydrase-based indicator system. These results suggest that zinc ion at high nM to microM levels can be accurately quantitated by FuraZin-1 ratiometrically or by Newport Green DCF by fluorescence lifetime; and at levels down to pM by intensity ratio, lifetime, or polarization using carbonic anhydrase-based systems.     

Biodirected epitaxial nanodeposition of polymers on oriented macromolecular templates

Biodirected epitaxial nanodeposition of polymers was achieved on a template with an oriented molecular surface. Acetobacter xylinum synthesized a ribbon of cellulose I microfibrils onto a fixed, nematic ordered substrate of glucan chains with unique surface characteristics. The substrate directed the orientation of the motion due to the inverse force of the secretion during biosynthesis, and the microfibrils were aligned along the orientation of the molecular template. Using real-time video analysis, the patterns and rates of deposition were elucidated. Field emission scanning electron microscopy revealed that a strong molecular interaction allowed for the deposition of nascent biosynthesized 3.5-nm cellulose microfibrils with inter-microfibrillar spacings of 7-8 nm on the surface of the template. The cellulose was deposited parallel to the molecular orientation of the template. Directed cellulose synthesis and ordered movement of cells were observed only by using a nematic ordered substrate made from cellulose, and not from ordered crystalline cellulose substrates or ordered cellulose-related synthetic polymers such as polyvinyl alcohol. This unique relationship between directed biosynthesis and the ordered fabrication from the nano to the micro scales could lead to new methodologies for the design of functional materials with desired nanostructures.     

Identification of the glutathione conjugate of 4-nitroquinoline 1-oxide formed in the reaction catalyzed by murine glutathione transferases

The product of the enzyme-catalyzed conjugation of glutathioneand 4-nitroquinoline 1-oxide was isolated and its structuredetermined by MS and NMR. The results indicate that the cysteinesulfur of glutathione replaces the nitro group of 4-nitroquinoline1-oxide in the reaction with the formation of 4-(glutathion-S-yI)-quinoline1-oxide. No evidence was found for the binding of glutathioneto any other position of 4-nitroquinoline 1-oxide or throughany group other than the cysteine sulfur.