Selection of molecules with desired properties from random pools of biopolymers has become a powerful tool in biotechnology. On designing an evolution experiment, a certain knowledge of the ...concomitant fitness landscape is clearly helpful to set up the optimal experimental conditions. The correlation function is a useful means of characterizing a given landscape, since it can be efficiently measured if one has a method of separating a pool of random sequences according to their Hamming distance from a moderately small number of test sequences. In this paper we describe a special type of hybridization chromatography, where a mixture of oligomers (partially) complementary to a given test sequence is hybridized to the test sequence, covalently bound to a matrix. DNA oligomers are eluted in an 'effective temperature gradient' using conditions that minimize the differences of effects of GC versus AT pairs on the melting temperatures. This method should be a means to quickly separate error classes and thus be the crucial step in characterizing fitness landscapes of biopolymers through an experimental approach. It would also be a useful tool to design sequence pools with a bias towards desired mutant spectra.
Proper timing of stabilization for spine injuries is discussed controversially. Whereas early repair of long bone fractures is known to reduce complications.
We investigated retrospectively 48 ...patients who were stabilized in a ventrodorsal approach for fractures of the thoracic spine. Patients were divided into three groups. All patients in groups I and II presented radiological or clinical signs of lung contusion. Patients were stabilized in the prone position via single-step dorsal stabilization with internal transpedicular fixation and ventral fusion with titanium cage or autologous bone graft using a minimally invasive video-assisted thoracotomy.
The average duration of the procedures in group I was 213+/-40 min, in group II 250+/-75 min, and in group III 255+/-65 min (p: n.s.). Intraoperative blood loss did not differ significantly between the three groups. The PaO(2)/FiO(2) ratio improved in groups I and III, whereas in group II an significant impairment of lung function occurred perioperatively. Postoperative ICU stay was comparable in groups I and II (I: 10+/-5 days; II: 9+/-7 days); overall ICU stay tended to be shorter in group I versus II. The postoperative dependence on ventilator support did not differ significantly among the three groups. The mortality rate was 0% in this series.
Our data provide further evidence that early stabilization of combined thoracic and thoracic spine injuries is safe, does not alter perioperative lung function, and results in a reduced overall ICU stay.
