RESUMO
Over a 1-year period the mode of fracture of the long bones of children's upper limbs was analysed. There were 277 fractures and 4 dislocations recorded. The most common fractures were of the distal radius and ulna. Most injuries were due to falls from a low height but those from a high fall necessitated hospital admission most frequently. Preventative measures are discussed.
Assuntos
Acidentes por Quedas , Acidentes , Traumatismos do Braço/etiologia , Fraturas Ósseas/etiologia , Adolescente , Fatores Etários , Criança , Pré-Escolar , Feminino , Traumatismos do Antebraço/etiologia , Humanos , Lactente , Recém-Nascido , Luxações Articulares/etiologia , MasculinoAssuntos
Adenosina/análogos & derivados , Escherichia coli/metabolismo , Isopenteniladenosina/análogos & derivados , Aminoacil-RNA de Transferência/metabolismo , Sulfitos/farmacologia , Isopenteniladenosina/metabolismo , Conformação de Ácido Nucleico , Sulfetos/metabolismo , Aminoacilação de RNA de Transferência/efeitos dos fármacosRESUMO
Escherichia coli tRNAPhe was modified by 3 M sodium bisulphite pH 6.0 for 24 h in the temperature range 25 degrees C (x 5 degrees C) to 55 degrees C and in the absence of added magnesium ions. The sites and extents of conversion of cytidines to uridine occurring at each temperature were determined by fingerprinting. The new sites of cytidine modification found at higher reaction temperatures were assumed to arise from breakage of secondary and tertiary structure hydrogen bonds involving cytidine residues. From these data, we conclude that hydrogen bonds within the 'complex core' of the tRNA (including the base pairs G-10 . C-25, C-11 . G-24 and C-13 . G-21 within the dihydrouridine stem and the tertiary structure base pair G-15 . C-48 melt at a lower temperature than the tertiary structure hydrogen bonds between G-19 in the dihydrouridine loop and C-56 in the TpsiC loop.
Assuntos
Escherichia coli/análise , RNA de Transferência , Sequência de Bases , Temperatura Alta , Ligação de Hidrogênio , Cinética , Conformação de Ácido Nucleico , Desnaturação de Ácido Nucleico , Oligorribonucleotídeos/análise , Fenilalanina , SulfitosRESUMO
Treatment of Escherichia coli CA265 phenylalanyl-tRNA with 3M-NaHSO3, pH6.0, at 25 degrees C resulted in modification of four bases and in the deacylation of the charged tRNAphe. The similarity of the rates of base modification and of the deacylation of the phenylalanyl-tRNA permitted the isolation of partially modified phenylalanyl-tRNAphe and partially modified deacylated tRNAphe. The sites and extents of base modification in these fractions were determined and found to be the same as those in uncharged tRNAphe modified under identical conditions. These findings are discussed in relation to previous evidence for and against a conformational change in tRNA on its aminoacylation. The methods described should prove adaptable to study of other aminoacyl-tRNA species.
Assuntos
Conformação de Ácido Nucleico/efeitos dos fármacos , Aminoacil-RNA de Transferência , Fenômenos Químicos , Química , Oligorribonucleotídeos/análise , Sulfitos/farmacologiaRESUMO
E coli tRNA2Phe was modified at 25 degrees C with 3M sodium bisulphite, pH6.0, for periods of up to 48 hours, Three cytadinine residues, at position 17, 74 and 75 from the 5' end were each deaminated to uridine. The 2-methylthio-N6-isopentenyl adenosine at position 37 formed a 1:1 bi-sulphite addition product which was stable to alkaii. No other residues were permanently modified. The rate of modification of each residue was first order with respect to remaining unmodified nucleotide, the time of half reaction, t1/2, being different for each residue. C17 reaction reacted at twice the rate of cytidine in PolyC, indicating that it occupied a very exposed position in the tRNA.
Assuntos
Escherichia coli/metabolismo , RNA Bacteriano , RNA de Transferência , Sulfitos/farmacologia , Sequência de Bases , Fenômenos Químicos , Química , Cinética , Conformação de Ácido Nucleico , Fenilalanina , Relação Estrutura-AtividadeAssuntos
Oxirredutases/metabolismo , Saccharomyces cerevisiae/enzimologia , Divisão Celular , Cicloeximida/farmacologia , DNA/análise , Fluoruracila/farmacologia , Cinética , Ribonucleotídeos , Saccharomyces cerevisiae/análise , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharomyces cerevisiae/crescimento & desenvolvimento , Fatores de Tempo , Trítio , UltrassomRESUMO
The synthesis of mitochondrial enzymes induced by exposure of anaerobically grown, lipid-depleted Saccharomyces cerevisiae to oxygen is inhibited by d(-)-threo-chloramphenicol and erythromycin. The concentration of these antibiotics required to cause 50% inhibition of this synthesis is less than 1 mm; this is also approximately the concentration required to inhibit by the same amount mitochondrial protein synthesis in situ. The synthesis of unsaturated fatty acids, ergosterol, and phospholipid induced by aeration is inhibited by d(-)-threo-chloramphenicol at high concentrations (12 mm) but is unaffected by erythromycin. l(+)-threo-Chloramphenicol affects neither enzyme nor lipid synthesis and is without effect on mitochondrial protein synthesis in situ. All three compounds inhibit the oxidative activity of isolated mitochondria; the chloramphenicol isomers also inhibit phosphorylation. In a euflavine-derived petite mutant, lacking mitochondrial protein synthesis and respiration, aeration results in the normal development of lipid in the cells, but no synthesis of mitochondrial enzymes. d(-)-threo-Chloramphenicol does not inhibit lipid synthesis in these cells. Thus inhibition of mitochondrial protein synthesis with erythromycin or genetic deletion of mitochondrial protein synthesis results in loss of the capacity to synthesize enzymes during aeration. d(-)-threo-Chloramphenicol, as well as inhibiting induced enzyme formation, inhibits lipid synthesis induced by oxygen. It is unlikely that the latter effect of chloramphenicol is due to inhibition of energy production and transformation, to direct effects on lipid synthesis, or to an inhibition of mitochondrial protein synthesis. It is, however, an effect not shared with the l isomer.
Assuntos
Cloranfenicol/farmacologia , Complexo IV da Cadeia de Transporte de Elétrons/biossíntese , Eritromicina/farmacologia , Hidroliases/biossíntese , Lipídeos/biossíntese , Saccharomyces/efeitos dos fármacos , Succinato Desidrogenase/biossíntese , Anaerobiose , Transporte de Elétrons/efeitos dos fármacos , Ácidos Graxos Essenciais/biossíntese , Fumaratos , Isomerismo , Mitocôndrias/enzimologia , Mitocôndrias/metabolismo , Fosforilação Oxidativa/efeitos dos fármacos , Consumo de Oxigênio/efeitos dos fármacos , Fosfolipídeos/biossíntese , Biossíntese de Proteínas , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharomyces cerevisiae/enzimologia , Saccharomyces cerevisiae/crescimento & desenvolvimento , Saccharomyces cerevisiae/metabolismo , Vitamina D/biossínteseRESUMO
The extent of development of respiratory function induced by aeration of an anaerobically grown unsaturated fatty acid auxotroph of Saccharomyces cerevisiae is determined by the availability, endogenous or externally supplied, of unsaturated fatty acid. The synthesis of mitochondrial and cytoplasmic enzymes during aeration appears to have a similar basis of regulation by available unsaturated fatty acid. Levels of unsaturated fatty acid that permit the synthesis of mitochondrial enzymes also result in a substantial stimulation of cellular protein synthesis.