Microbial penetration and utilization of organic aircraft fuel-tank coatings

Microorganisms have been found as contaminants in various types of aircraft fuel tanks. Their presence introduces problems in the operation of the aircraft, including destruction of components such as the organic coatings used as protective linings in the fuel tanks. Microbial penetration and utilization of the currently used organic coatings, EC 776, DV 1180, PR 1560, and DeSoto 1080, were determined by changes in electrical resistances of the coatings; mycelial weight changes; growth counts of the bacteria; and manometric determinations on Pseudomonas aeruginosa (GD-FW B-25) and Cladosporium resinae (QMC-7998). The results indicate EC 776 and DV 1180 to be less resistant to microbial degradation than the other coatings. Organic coatings, serving as a source of nutrition, would be conducive to population buildups in aircraft fuel tanks.     

Prevalence and distribution of Sarcocystis spp. among white-tailed deer of the southeastern United States

Sarcocysts were found by light microscopic examination of muscle in 199 (51%) of 390 white-tailed deer (Odocoileus virginianus) from the southeastern United States. Sarcocystis infections were detected more frequently in histologic sections of tongue (45%) than of heart (9%). Sarcocysts were significantly more prevalent in adult deer (54%) than fawns (26%) (P less than .01). Statistically significant differences in prevalence were not found in deer from different physiographic provinces or between sexes. Artificial digestion was more sensitive in detecting Sarcocystis infections than examination of histologic sections when both techniques were used to examine tongues of 35 deer. Three different size sporocysts, possibly representing at least two species of Sarcocystis, were recovered during feeding trials. Seven dogs (Canis familiaris) shed sporocysts 9 to 12 days after eating infected venison. Sporocysts measured 13.4-16.8 x 9.0-12.3 micrometers with an average measurement of 15.2 x 10.9 micrometers (N = 195). One of three cats (Felis catus) and one of two red foxes (Vulpes vulpes) first shed sporocysts of Sarcocystis 10 days after eating infected venison. Sporocysts from the cat measured 11.2-13.4 x 6.72-8.96 micrometers (avg 12.0 x 8.7 micrometers, N = 18), and those from the fox measured 11.2-15.7 x 9.0-11.2 micrometers (avg 13.6 x 10.2 micrometers, N = 7).     

Effect of cisplatin upon expression of in vivo immune tumor resistance

The major intent of cancer treatment with cytotoxic drugs is direct tumor cell damage, but some of these drugs have been shown to be immunomodulatory. Cisplatin is a widely used cytotoxic drug that has been combined with biological response modifiers in recent clinical trials. To evaluate further whether cisplatin may independently alter the level of host resistance against tumor growth, the drug was tested in the Mc7 sarcoma rat tumor model. The expression of in vivo tumor resistance against Mc7 sarcoma in syngeneic Wistar rats is mediated by circulating non-cytotoxic T lymphocytes. These cells interact specifically with tumor cells to generate cytotoxic effectors locally at the site of a tumor challenge. Activities of these components of expression of tumor resistance were measured in vivo after administration of cisplatin and dose-dependent effects were found. Low-dose cisplatin (0.3 mg/kg) increased the activity of the circulating lymphocytes that mediate tumor resistance, and high-dose cisplatin (9 mg/kg) suppressed both mediator lymphocyte activity and the generation of antitumor effector mechanisms. These studies suggest that low-dose cisplatin may be immunomodulatory and combining it with biological response modifiers might be a useful strategy. However, high-dose cisplatin given with biological response modifiers may negate potential immunomodulatory activities of such agents.     

Energetic aspects of CO oxidation in desulfovibrio desulfuricans

In cell suspension of Desulfovibrio desulfuricans B-1388, oxidation of CO as the only energy source is associated with reduction of SO42-. After a 2-h incubation of cells in 8% CO, 81% of the gas is converted. Oxidation of 1 mole CO results in formation of 0.23 mole H2S. Intracellular ATP content increases from 2.5 (control) to 8.3 nmoles/mg (during CO conversion). Dinitrophenol inhibits sulfate reduction and CO oxidation. CO dehydrogenase was detected in cytoplasmic and membrane cell fractions (59 and 34%, respectively).     

Supplemental carbohydrate ingestion does not improve performance of high-intensity resistance exercise

The effects of supplemental carbohydrate (CHO) ingestion on the performance of squats to exhaustion (STE) were investigated with eight resistance-trained men. Subjects participated in a randomized, counterbalanced, double-blind, placebo-controlled protocol with testing separated by 7 days. Subjects consumed 0.3g.kgCHO.bodymass or a placebo (PLC) of equal volume immediately before exercise and after every other successful set of squats. The STE consisted of sets of five repetitions at an intensity of 85% 1 repetition maximum (1RM). Performance measured as total sets (CHO 3.5 +/- 3.2, PLC 3.5 +/- 2.7), repetitions (CHO 20.4 +/-14.9, PLC 19.7 +/- 13.1), volume load (CHO 2928.7 +/- 2219.5 kg, PLC 2772.8 +/- 1951.4 kg), and total work (CHO 29.9 +/- 22.3 kJ, PLC 28.6 +/- 19.5 kJ) was not statistically different between the CHO and PLC treatments. The results suggest that CHO supplementation does not enhance performance of squats performed with 85% 1RM to volitional failure.     

Mitochondrial displacements in response to nanomechanical forces

Mechanical stress affects and regulates many aspects of the cell, including morphology, growth, differentiation, gene expression and apoptosis. In this study we show how mechanical stress perturbs the intracellular structures of the cell and induces mechanical responses. In order to correlate mechanical perturbations to cellular responses, we used a combined fluorescence-atomic force microscope (AFM) to produce well defined nanomechanical perturbations of 10 nN while simultaneously tracking the real-time motion of fluorescently labelled mitochondria in live cells. The spatial displacement of the organelles in response to applied loads demonstrates the highly dynamic mechanical response of mitochondria in fibroblast cells. The average displacement of all mitochondrial structures analysed showed an increase of approximately 40%, post-perturbation ( approximately 160 nm in comparison to basal displacements of approximately 110 nm). These results show that local forces can produce organelle displacements at locations far from the initial point of contact (up to approximately 40 microm). In order to examine the role of the cytoskeleton in force transmission and its effect on mitochondrial displacements, both the actin and microtubule cytoskeleton were disrupted using Cytochalasin D and Nocodazole, respectively. Our results show that there is no significant change in mitochondrial displacement following indentation after such treatments. These results demonstrate the role of the cytoskeleton in force transmission through the cell and on mitochondrial displacements. In addition, it is suggested that care must be taken when performing mechanical experiments on living cells with the AFM, as these local mechanical perturbations may have significant structural and even biochemical effects on the cell.