ABSTRACT
BACKGROUND: Infections are a frequent cause of morbidity and mortality among postoperative liver transplant (OLT) patients and a leading cause of decompensated chronic liver disease (CLD) among patients awaiting the procedure. Oral lesions that are frequently observed in subjects with CLD may represent foci for systemic infections before and after OLT. AIMS: To evaluate the oral health profile of patients with CLD awaiting OLT. METHODS: One hundred thirty one patients including 100 males of overall mean age 49.5 ± 10.8 years with CLD were listed for OLT and examined for oral health status according to a established protocol. RESULTS: One hundred thirty (99%) patients were partially edentulous; 66 (51%) had chewing difficulties; and 63 (48%) experienced reduced salivary flow. With respect to periodontal disease and oral infections, 68 (25%) had periodontitis, 63 (48%) had periapical lesion, 64 (49%) had abscesses, and 59 (45%) had root fragments. Loss of follow-up was observed in 21 subjects. Among the 110 other patients, 63 (57%) underwent dental treatments with complications in only two cases. Interestingly, mortality was significantly lower among treated (31%) versus nontreated patient (79%; P<.001). CONCLUSIONS: Poor oral health status observed in most CLD patients may represent a source of systemic infections before and after OLT. Treatment of such lesions was feasible in the majority of the patients and seemed to be associated with a reduction in mortality.
Subject(s)
Liver Cirrhosis/surgery , Liver Transplantation , Mouth Diseases/complications , Oral Health , Waiting Lists , Adult , Brazil , Chi-Square Distribution , Female , Humans , Liver Cirrhosis/mortality , Male , Middle Aged , Mouth Diseases/diagnosis , Mouth Diseases/microbiology , Mouth Diseases/mortality , Mouth Diseases/therapy , Risk Assessment , Risk Factors , Waiting Lists/mortalityABSTRACT
We have analyzed the relative G,C content from protein coding regions of 530 organisms and found that the ratio of the G,C content of the codons of the amino acids corresponding to Class II and Class I aminoacyl-tRNA synthetases decreases in a statistically significant way from prokaryotes to animals. This can be interpreted assuming that an initial asymmetry between the G,C content of codons of Class I and II amino acids existed and has decreased in the course of evolution.
Subject(s)
Amino Acyl-tRNA Synthetases/classification , Amino Acyl-tRNA Synthetases/genetics , Evolution, Molecular , Amino Acids/genetics , Animals , Archaea/enzymology , Archaea/genetics , Bacteria/enzymology , Bacteria/genetics , Base Composition , Codon , Eukaryotic Cells/enzymology , Monte Carlo Method , Vertebrates/geneticsABSTRACT
As a consequence of the existence of two classes of aminoacyl-tRNA synthetases (aaRSs), we defined two types of mutations: g (mutations that do not change the class of the involved amino acids) and u (those which change the class). We have found that the mean chemical distance resulting from g mutations is smaller than that corresponding to u mutations, indicating that g mutations are responsible for most of the known minimization of the genetic code. This supports models for the origin and evolution of the code, in which new amino acids were added after duplications or modification of existing aaRSs.
Subject(s)
Amino Acyl-tRNA Synthetases/genetics , Genetic Code/genetics , Mutation , Amino Acids/genetics , Animals , Codon , Humans , Models, Genetic , Mutation, Missense , Point MutationABSTRACT
We compare predictions from a proposed model for the origin of the genetic code (J. Theor. Biol (1993) 164, 291-305) with existing information on the base content of codons and abundance of amino acid in different organisms. A comparison is also made between the three groups of amino acids suggested by the model and the two classes of aminoacetyl-tRNA synthetases. The observed agreements tend to support the model.
Subject(s)
Genetic Code , Amino Acids/genetics , Amino Acyl-tRNA Synthetases/classification , Amino Acyl-tRNA Synthetases/genetics , Animals , Base Composition , Codon/genetics , Humans , Models, GeneticABSTRACT
The probability of randomly synthesized peptides having an excess of a given residue Ri (nRi > N/2; N = size of the peptide) decreases strongly with peptide size. For a strong specific interaction of a Ri, rich peptide with a given sequence of a ribotide chain, peptides should be reasonably large. We discuss how a compromise can be achieved that may have had an important role on the origin of the genetic code.