Measuring driver impairments: sleepiness, distraction, and workload

Snow was falling heavily when Sarah was driving on a slippery road to her cousin's country cottage. It was dark outside, and the visibility was poor. She had planned to arrive before sunset, but the rental service had made a mistake, and it took hours before she got her rental car at the airport. It was past midnight now, and after a long day of traveling, Sarah was starting to get sleepy. Fortunately, there were only 15 km to go, but her eyelids were starting to feel heavy. To stay awake, she put her favorite CD on, turned up the volume, and started to sing along. This seemed to help a little-good-only 10 km to go. This was when Sarah's phone started ringing, and she awkwardly tried to find the mute button for the car stereo while answering the phone. As she looked up again, she barely caught a glimpse of the red brake lights of the car in front of her as she smashed into it.     

Biological and chemical effects of mustard gas in yeast.

Mustard gas induces inactivation and mutation in yeast. Both effects are dose-proportional, indicating single-hit events. Induction of both effects is influenced by the cell's capacity for DNA dark-repair, whereby the probability of reversion is highest in repair-proficient cells. Binding of mustard gas to cells and probably to DNA is independent of DNA-repair systems. The number of inter-strand cross-links, as determined by assaying for renaturability of alkalidenatured DNA, increases in a dose-proportional manner. At 37% survival an excision-deficient strain contains 55 inter-strand cross-links. Chromatographic analysis yields several alkylation products of DNA. Their relative frequencies resemble the values reported for E. coli and bacteriophage T7.     

Hydrolysis of exogenous ATP by isolated frog gastric mucosa

ATP, added to the solution bathing the nutrient (serosal) surface of isolated frog gastric mucosa, was found to break down rapidly to ADP, inorganic phosphate and other products. This activity is due to an ectoenzyme, i.e., to an enzyme system easily accessible to the bathing solution. This conclusion follows from experiments which showed that penetration of ATP into the mucosal cells occurred at a much slower rate: leakage of inorganic phosphate and adenine nucleotides from mucosal cells was also minor. The surface ATPase may reflect the operation of a mechanism at the nutrient surface involved in acid secretion.     

Altered dark- and photoconversion of phytochrome B mediate extreme light sensitivity and loss of photoreversibility of the phyB-401 mutant

The phyB-401 mutant is 10(3) fold more sensitive to red light than its wild-type analogue and shows loss of photoreversibility of hypocotyl growth inhibition. The phyB-401 photoreceptor displays normal spectral properties and shows almost no dark reversion when expressed in yeast cells. To gain insight into the molecular mechanism underlying this complex phenotype, we generated transgenic lines expressing the mutant and wild-type phyB in phyB-9 background. Analysis of these transgenic lines demonstrated that the mutant photoreceptor displays a reduced rate of dark-reversion but normal P(fr) to P(r) photoconversion in vivo and shows an altered pattern of association/dissociation with nuclear bodies compared to wild-type phyB. In addition we show (i) an enhanced responsiveness to far-red light for hypocotyl growth inhibition and CAB2 expression and (ii) that far-red light mediated photoreversibility of red light induced responses, including inhibition of hypocotyl growth, formation of nuclear bodies and induction of CAB2 expression is reduced in these transgenic lines. We hypothesize that the incomplete photoreversibility of signalling is due to the fact that far-red light induced photoconversion of the chromophore is at least partially uncoupled from the P(fr) to P(r) conformation change of the protein. It follows that the phyB-401 photoreceptor retains a P(fr)-like structure (P(r) (*)) for a few hours after the far-red light treatment. The greatly reduced rate of dark reversion and the formation of a biologically active P(r) (*) conformer satisfactorily explain the complex phenotype of the phyB-401 mutant and suggest that amino acid residues surrounding the position 564 G play an important role in fine-tuning phyB signalling.     

Physiology and pathophysiology of nitrosative and oxidative stress in osteoarthritic joint destruction

Osteoarthritis (OA) is one of the most common chronic diseases, with increasing importance due to increased life expectancy. On a cellular level, the pathophysiology of joint function impairment and ultimate destruction associated with OA remains poorly understood. Free radicals are highly reactive molecules involved in both normal intracellular signal transduction and degenerative cellular processes. An imbalance between the free radical burden and cellular scavenging mechanisms, defined as oxidative stress, has been identified as a relevant factor in OA pathogenesis. This literature review elucidates the involvement of nitrosative and oxidative stress in cellular ageing in joints, cell senescence, and apoptosis. Free radical exposure is known to promote cellular senescence and apoptosis, and the involvement of radical oxygen species (ROS) in inflammation, fibrosis control, and pain nociception has been proven. A relatively novel approach to OA pathophysiology considers the joint to be a dynamic system consisting of 3, continuously interacting compartments, cartilage, synovial tissue, and subchondral bone. Current knowledge concerning free radical involvement in paracrine signalling in OA is reviewed. The interrelationship between oxidative imbalances and OA pathophysiology may provide a novel approach to the comprehension, and therefore modification, of OA disease progression and symptom control.