The role of recombination in evolutionary adaptation of Escherichia coli to a novel nutrient.

The benefits and detriments of recombination for adaptive evolution have been studied both theoretically and experimentally, with conflicting predictions and observations. Most pertinent experiments examine recombination's effects in an unchanging environment and do not study its genomewide effects. Here, we evolved six replicate populations of either highly recombining R+ or lowly recombining R- E. coli strains in a changing environment, by introducing the novel nutrients L-arabinose or indole into the environment. The experiment's ancestral strains are not viable on these nutrients, but 130 generations of adaptive evolution were sufficient to render them viable. Recombination conferred a more pronounced advantage to populations adapting to indole. To study the genomic changes associated with this advantage, we sequenced the genomes of 384 clones isolated from selected replicates at the end of the experiment. These genomes harbour complex changes that range from point mutations to large-scale DNA amplifications. Among several candidate adaptive mutations, those in the tryptophanase regulator tnaC stand out, because the tna operon in which it resides has a known role in indole metabolism. One of the highly recombining populations also shows a significant excess of large-scale segmental DNA amplifications that include the tna operon. This lineage also shows a unique and potentially adaptive combination of point mutations and DNA amplifications that may have originated independently from one another, to be joined later by recombination. Our data illustrate that the advantages of recombination for adaptive evolution strongly depend on the environment and that they can be associated with complex genomic changes.

Myelotomy reduces spinal cord edema and inhibits aquaporin-4 and aquaporin-9 expression in rats with spinal cord injury.

OBJECTIVE: Spinal cord edema contributes to the pathophysiological mechanisms underlying spinal cord injury (SCI) and is associated with functional recovery after SCI. Early myelotomy may be a promising surgical intervention for reducing SCI-induced edema. However, it remains unclear whether myelotomy can reduce SCI-induced edema. In addition, aquaporin-4 (AQP4) and aquaporin-9 (AQP9) have important roles in the regulation of water homeostasis. Here, we aimed to determine the effects of myelotomy on AQP4 and AQP9 expression and spinal cord edema in a rat model of moderate SCI. METHODS: Rats were randomly assigned to three groups: the sham control group (n=22) receiving laminectomy alone; the contusion group (n=44) receiving laminectomy plus contusion; and the myelotomy group (n=44) receiving laminectomy plus contusion followed by myelotomy at 24 h. Functional recovery was estimated by the open-field and inclined plane tests. Spinal cord edema was determined by measuring the water content. The expression of AQP4 and AQP9 was determined by western blot. RESULTS: Compared with the contusion group, myelotomy significantly improved the Basso, Beattie and Bresnahan scores in the open-field test and resulted in a higher mean angle value in the incline plane test. Myelotomy significantly reduced SCI-induced edema at 4 and 6 days after SCI, which was accompanied by downregulation of AQP4 and AQP9 expression. CONCLUSION: Myelotomy improves locomotor function, reduces edema in rats with SCI and is associated with decreased expression of AQP4 and AQP9.

Optimal time window of myelotomy in rats with acute traumatic spinal cord injury: a preliminary study.

OBJECTIVES: Pathophysiological mechanisms underlying spinal cord injury (SCI) partially involve edema and formation of a hematoma. Myelotomy seems to be a promising intervention. However, the appropriate timing of myelotomy is still unknown in SCI. Here we aimed to determine the timing of microsurgical myelotomy in an animal model of SCI. METHODS: The SCI model was contusion-induced with a new york university impactor. Sixty-five adult female rats were randomly divided into the following groups: laminectomy alone (the 'sham group', SG), laminectomy plus contusion (the 'contusion group', CG) or laminectomy plus contusion followed by myelotomy at 8, 24 or 48 h (8 h-MTG [myelotomy-treated group], 24 h-MTG or 48 h-MTG). Functional recovery was evaluated via the open field test and the inclined plane test every week after SCI. The percentage of spared white matter area (SWMA) and ultrastructure characteristics of the injured dorsolateral spinal cord were determined on the 42nd day after SCI. RESULTS: Compared with the CG, myelotomy at 8 h-MTG or 24 h-MTG greatly improved the BASSO-BEATTIE- BRESNAHAN scores (P<0.008), whereas the 48 h-MTG showed less efficacy (P=0.023). All myelotomy groups showed higher mean angle values in an inclined plane test (P<0.005) and had greater percentages of SWMA than the CG. Rats in the 24 h-MTG showed a higher intra-axonal fraction and myelin fraction than those in 48 h-MTG (P<0.005). CONCLUSION: Myelotomy up to 48 h after SCI improves recovery in rats. The potential time window of myelotomy may be between 8 and 24 h after SCI.

Profound thrombocytopenia associated with piperacillin in a hemodialysis patient.

Piperacillin-induced thrombocytopenia, albeit reversible, is a life-threatening hematological emergency but easily overlooked. We describe a 78-year-old uremic man on regular hemodialysis who received intravenous administration of piperacillin (2 g) 3 times a day to treat nosocomial pneumonia. On the eighth day of therapy, isolated profound thrombocytopenia with a nadir value of 3 x 103/mm3 was noticed. Physical examination revealed multiple bruises over puncture sites and petechiae over bilateral lower extremities. An exhaustive search for potential causes of thrombocytopenia was unrevealing. Upon withdrawal of piperacillin and immediate high-flux hemodialysis, platelet count rapidly normalized up to 215 x 103/ mm3 in 3 days. With the widespread use of piperacillin, early recognition of piperacillin-induced immune thrombocytopenia and prompt withdrawal of the causative antibiotic may achieve less morbidity.

Effects of piroxicam-beta-cyclodextrin sachets on abnormal postural sway in patients with chronic low back pain.

BACKGROUND: The clinical effects of piroxicam-beta-cyclodextrin (PBC) in sachet form have been surveyed in patients with osteoarthritic or acute pain in western countries, but scarcely studied in those with chronic low back pain (LBP), and never investigated in the field of postural sway. The aim of this study was to evaluate the clinical effects of PBC in sachet form prescribed in patients with chronic backache in local Asian when compared with those of plain piroxicam. METHODS: After randomized allocation and experimental exclusion, a total of 42 eligible patients were randomized into two groups, the sachet group (n = 23) and the piroxicam tablet group (n = 19). Both groups were administered the same dosage, orally per day (daily dose = 20 mg). The duration of trial was 28 days. Efficacy was assessed with pain score, disability index and postural sway. RESULTS: The patients in sachet group showed greater improvement in pain score and disability index than those who took piroxicam tablets. There were significantly lower sway velocity and intensity at almost all different conditions than baseline profiles in both groups (P < 0.05). However, there was no significant difference of sway velocity and intensity in the piroxicam tablets group with regard to eyes open or eyes closed in 20 degrees dorsiflexion. CONCLUSIONS: Piroxicam-beta-cyclodextrin (PBC) sachet may have greater improvement in the treatment of chronic LBP and possess the extended effects on postural abnormality relevant to chronic LBP.

Curcuminoids purified from turmeric powder modulate the function of human multidrug resistance protein 1 (ABCC1).

Multidrug resistance is a major cause of chemotherapy failure in cancer patients. One of the resistance mechanisms is the overexpression of drug efflux pumps such as P-glycoprotein and multidrug resistance protein 1 (MRP1, (ABCC1)). In this study, curcumin mixture and three major curcuminoids purified from turmeric (curcumin I, II, and III) were tested for their ability to modulate the function of MRP1 using HEK293 cells stably transfected with MRP1-pcDNA3.1 and pcDNA3.1 vector alone. The IC(50) of curcuminoids in these cell lines ranged from 14.5-39.3 microM. Upon treating the cells with etoposide in the presence of 10 microM curcuminoids, the sensitivity of etoposide was increased by several folds only in MRP1 expressing and not in pcDNA3.1-HEK 293 cells. Western blot analysis showed that the total cellular level of MRP1 protein level was not affected by treatment with 10 microM curcuminoids for three days. The modulatory effect of curcuminoids on MRP1 function was confirmed by the inhibition of efflux of two fluorescent substrates, calcein-AM and fluo4-AM. Although all the three curcuminoids increased the accumulation of fluorescent substrates in a concentration-dependent manner, curcumin I was the most effective inhibitor. In addition, curcuminoids did not affect 8-azido[alpha-(32)P]ATP binding, however they did stimulate the basal ATPase activity and inhibited the quercetin-stimulated ATP hydrolysis of MRP1 indicating that these bioflavonoids interact most likely at the substrate-binding site(s). In summary, these results demonstrate that curcuminoids effectively inhibit MRP1-mediated transport and among curcuminoids, curcumin I, a major constituent of curcumin mixture, is the best modulator.