Reconstruction of lower lip defects after tumor excision: an aesthetic and functional evaluation.

We are presenting a new questionnaire to evaluate the functional and aesthetic aspects after reconstruction of defects of the lower lip resulting from tumor excision. The questionnaire is based on objective parameters with numerical values. The application of the questionnaire is carried out based on 2 different surgical techniques, which have been used in the Department of Oral and Maxillofacial Surgery of La Princesa University Hospital in Madrid. These techniques are used in the reconstruction of surgical defects and concern the location and percentage of the lip resection. These techniques are the rotation-advancement flap by Yu and the rotation-advancement in island flap by Colmenero et al. The defects are located laterally and they include 40% to 60% of the length of the lip, avoiding the commissure. There is also one case with a defect that is almost 100% of the length of the lip. According to the questionnaire, we conclude that in unilateral defects that exceed 50% (up to 70%), Yu's technique provides better results from an aesthetic and functional point of view than Colmenero's technique. In subtotal defects, bilateral Yu flaps provide optimum function, with good position of the scars. This is a technique to be considered when confronted with extensive defects of the lip that do not include the commissures.

The strongly conserved lysine 256 of Saccharomyces cerevisiae phosphoenolpyruvate carboxykinase is essential for phosphoryl transfer.

Lysine 256, a conserved amino acid of Saccharomycescerevisiae phosphoenolpyruvate (PEP) carboxykinase located in the consensus kinase 1a sequence of the enzyme, was changed to alanine, arginine, or glutamine by site-directed mutagenesis. These substitutions did not result in gross changes in the protein structure, as indicated by circular dichroism, tryptophan fluorescence spectroscopy, and gel-exclusion chromatography. The three variant enzymes showed almost unaltered Km for MnADP but about a 20 000-fold decrease in Vmax for the PEP carboxylation reaction, as compared to wild-type PEP carboxykinase. The variant enzymes presented oxaloacetate decarboxylase activity at levels similar to those of the native protein; however, they lacked pyruvate kinase-like activity. The dissociation constant for the enzyme-MnATP complex was 1.3 +/- 0.3 microM for wild-type S. cerevisiae PEP carboxykinase, and the corresponding values for the Lys256Arg, Lys256Gln, and Lys256Ala mutants were 2.0 +/- 0.6 microM, 17 +/- 2 microM, and 20 +/- 6 microM, respectively. These results collectively show that a positively charged residue is required for proper binding of MnATP and that Lys256 plays an essential role in transition state stabilization during phosphoryl transfer for S. cerevisiae PEP carboxykinase.

Interaction of adenosine nucleotide analogs with Saccharomyces cerevisiae phosphoenolpyruvate carboxykinase.

The substrate characteristics and interactions of different adenosine nucleotide analogs with Saccharomyces cerevisiae phosphoenolpyruvate (PEP) carboxykinase were investigated by steady-state kinetic analysis and calculations of interaction energies. Comparison of Vmax/Km values showed that analogs substituted at C8 in the adenine ring (8-Br-ATP, 8-N3-ATP, 8-N3-ADP) gave almost the same kinetic values as ATP and ADP, whereas those substituted in the ribose hydroxyls (3'(2')-O-(N-methylanthraniloyl)-ATP (MANT-ATP), 3'(2')-O-(N-methylanthraniloyl)-ADP (MANT-ADP), 2'(3')-O-(2,4,6-trinitrophenyl)-ADP (TNP-ADP), 2'(3')-O-(2,4,6-trinitrophenyl)-ATP (TNP-ATP)) showed 1-8% the value for the corresponding physiological substrate. A comparison between the experimental results and molecular mechanics calculations was performed, employing a model for the S. cerevisiae PEP carboxykinase-ATP-Mn2+ complex. The calculated interaction energies of S. cerevisiae PEP carboxykinase with ATP, MANT-ATP, TNP-ATP, 8-Br-ATP, and 8-N3-ATP were linearly related (correlation coefficient 0.92) with -ln(Vmax/Km). This good correlation supports the proposal that the interaction of the substituent with the enzyme affects the interaction of the common region of ATP with the active site, thus leading to effects in Vmax.