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Results for “Comparative evolution”

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At least 271 records · Page 15Linked to original sources
PubMed1976

Cyclophosphamide (CP) substituting azathioprine after renal transplantation.

Eighteen patients received CP substituting AZ after renal transplantation following evidence of hepatitis. We have compared graft evolution before and after treatment with CP. Twelve patients showed no modification in graft evolution. In four patients the renal function decreased but it did not seem attributable to the change of the drug. Two patients showed intolerance attributable to the change of the drug. In one patient who received CP instead of AZ since the data of the transplant onwards, with no evidence of hepatic lesion, renal function decreased but this did not seem attributable to the use of the drug. The dose of CP in renal transplantation is discussed. We conclude that CP is a good substitute for AZ in renal transplanted patients. Adequate doses seemed to range between 0.7 and 1 mg/kg/day.

Azathioprine↗
PubMedDate not supplied

[Results of a school addictive substances abuse prevention program: the Barcelona PASE pilot project].

A pilot project for the prevention of substance abuse in schools (PASE) has been developed in 1988-90 in sixth and seventh grades (12-14 years-old) in 11 primary schools in the city of Barcelona (Spain). Data on consumption smoking, alcohol and drugs were obtained before the implementation of the project, shortly afterwards, and in the next school year. These results are presented, comparing the evolution of attitudes, beliefs and behavior of these school children with a control group composed of students from reference schools. The results suggest a modest but significant effect of the program, which seems to decrease over time for smoking, suggesting the need for booster interventions to maintain its effects.

Adolescent↗
PubMed1993

The effects of ventilation tube placement on hearing, speech, language, cognition and behaviour.

As a part of a larger, multidimensional study on secretory otitis media (SOM) and its relation to children's development, the effects of ventilation tube (VT) placement on hearing, speech, language, cognition and behaviour were studied over a six month period. Children with a clear and persistent picture of SOM were examined just before tubes were inserted and again, with the same measures, six months later. Their evolution was compared to that of a control group. The results indicate, as was expected, that the hearing of the children with SOM normalized very quickly after surgery. Speech and expressive language functions were comparable for both groups at the two moments of examination. Only verbal comprehension of the SOM-group was found to be slightly improved in the course of a six month period. No differences in general cognitive functioning and in behaviour were found between both groups.

Child Behavior↗
PubMed1997

Molecular phylogenetics of bacterial endosymbionts and their vestimentiferan hosts.

Vestimentiferan tube worms from deep-sea hydrothermal vents and cold-water seeps rely entirely on sulfur-oxidizing bacterial endosymbionts for nutriment. We examined host-symbiont co-evolution by comparing phylogenetic trees from symbiont 16S ribosomal DNA and host mitochondrial COI genes. The endosymbionts comprised two distinct clades, one associated with tube worms from basaltic vent habitats and the other associated with tube worms from sedimented seep-like environments. Within each symbiont clade, 16S rDNA sequences were nearly identical, suggesting that vent vestimentiferans share a single endosymbiont species that is distinct from the seep endosymbiont species. A third endosymbiont type, related to the seep species, was found in a tube worm collected from a whale carcass. Our results are consistent with a horizontal model of symbiont transmission.

Animals↗
PubMed1997

[Our experience in portal cavernomatosis in childhood: cross-sectional study and analysis of results].

A retrospective and transversal study of our patients with portal cavernomatosis is developed, with the aim of comparing the evolution and the present status of the patients that have undergone different therapeutical approaches. Between 1975 and 1995, 15 patients with portal cavernomatosis have been treated. Personal history, signs and symptoms at the moment of diagnosis, and treatment were analyzed. Now, the controls have been made by physical examination and ECO-Doppler of the espleno-portal system. In 6 cases the absence of bleeding made surgery unnecessary. In the 9 patients with digestive haemorrhage, it could be controlled pharmacologically, with a later surgical approach. Now, all non-operated and 6 operated patients show splenomegaly, without bleeding. The ECO-Doppler shows colateral flow, the splenomegaly in the non-operated and the surgical shunts and the hepatofugal circulation in the operated patients. Looking at our results, we believe that prophylactic surgery is not indicated. In those cases of digestive bleeding, surgery after the complete resolution of the acute disease shows good results at a short and long term.

Child, Preschool↗
PubMed1998

Trends in childhood cancer mortality as indicators of the quality of medical care in the developed world.

BACKGROUND: Mortality from childhood cancer in general and childhood leukemia in particular has sharply declined in economically developed countries over the last 30 years, whereas the incidence of these diseases has remained essentially unaltered. Therefore, childhood malignancies can be used as tracers of accessibility to and effectiveness of medical care. The objective of this study was to compare the reduction of mortality from childhood cancer in general, and childhood leukemia in particular, in four economically developed areas of the world, to assess accessibility to and effectiveness of technologically advanced medical care. METHODS: The authors used data from the World Health Organization to compare the evolution over time of gender specific, age-adjusted mortality from childhood cancer in general and childhood leukemia in particular in the childhood (birth to age 14 years) populations of North America, western Europe, Japan, and Australia and New Zealand during the period 1960-1993. They assessed the evolution over time and the cumulative percentage representing the decline in mortality from childhood cancer and childhood leukemia in the four aforementioned areas of the world. RESULTS: The decline in mortality from both the disease entities considered and for both genders has been more pronounced in North America than in other economically developed areas of the world. CONCLUSIONS: When disease control depends on technologically advanced medical care, as in the case of cancer, the North American population is benefited by earlier and effective introduction of new therapeutic approaches. This conclusion does not apply to other childhood diseases, the incidence of which is higher among low-income groups and control of which depends on prevention rather than treatment.

Adolescent↗
PubMed1985

Histones in protistan evolution.

The potential of comparative studies on histones for use in protistan evolution is discussed, using algal histones as specific examples. A basic premise for the importance of histones in protistan evolution is the observation that these proteins are completely absent in prokaryotes (and cytoplasmic organelles), but with few exceptions, the same five major histone types are found in all higher plants and animals. Since the histone content of the algae and other protists is not constant, some of these organisms may represent transition forms between the prokaryotic and eukaryotic modes of packaging the genetic material. Comparative studies of protistan histones may thus be of help in determining evolutionary relationships. However, several problems are encounter with protistan histones, including difficulties in isolating nuclei, proteolytic degradation, anomalous gel migration of histones, and difficulties in histone identification. Because of the above problems, and the observed variability in protistan histones, it is suggested that several criteria be employed for histone identification in protists.

Animals↗
PubMed1990

Extreme differences in charge changes during protein evolution.

The maintenance of a proper distribution of charged amino acid residues might be expected to be an important factor in protein evolution. We therefore compared the inferred changes in charge during the evolution of 43 protein families with the changes expected on the basis of random base substitutions. It was found that certain proteins, like the eye lens crystallins and most histones, display an extreme avoidance of changes in charge. Other proteins, like phospholipase A2 and ferredoxin, apparently have sustained more charged replacements than expected, suggesting a positive selection for changes in charge. Depending on function and structure of a protein, charged residues apparently can be important targets for selective forces in protein evolution. It appears that actual biased codon usage tends to decrease the proportion of charged amino acid replacements. The influence of nonrandomness of mutations is more equivocal. Genes that use the mitochondrial instead of the universal code lower the probability that charge changes will occur in the encoded proteins.

Biological Evolution↗
PubMed1996

Enlarged similarity of nucleic acid sequences.

The concept of nucleic acid sequence base alternations is presented. The number of base alterations for the sequences of different length is established. The definition of "enlarged similarity" of nucleic acids sequences on the basis of sequence base alterations is introduced. Mutual information between sequences is used as a quantitative measure of enlarged similarity for two compared sequences. The method of mutual information calculation is developed considering the correlation of bases in compared sequences. The definitions of correlated similarity and evolution similarity between compared sequences are given. Results of the use of enlarged similarity approach for DNA sequences analysis are discussed.

Base Sequence↗
PubMed1981

Experimental evolution of propanediol oxidoreductase in Escherichia coli. Comparative analysis of the wild-type and mutant enzymes.

A model for the study of experimental evolution is provided by the novel metabolic system responsible for the progressive utilization of L-1,2-propane-diol by mutants of Escherichia coli (strains 3 and 430). In these mutant strains, propanediol oxidoreductase, which serves as L-lactaldehyde reductase in fucose fermentation by wild-type cells, became a key enzyme for aerobic catabolism of propanediol. In the wild-type strain (strain 1), the enzyme is inducible only anaerobically; in strains 3 and 430, the enzyme is synthesized constitutively even in the presence of air. The propanediol oxidoreductase from all three strains was purified to homogeneity by the same procedure. The enzyme of strain 3 clearly differed from that of strain 1 in several respects: Km and V in both directions of the reaction, energy of activation, thermal stability, pH optimum and substrate specificity. However, no difference in any of the above characteristics was found between the enzymes of strains 3 and 430. All three enzymes presented the same electrophoretic mobility. According to immunological data, all three strains differed in their intracellular enzyme level.

Alcohol Oxidoreductases↗
PubMed1997

Evolution and significance of circulating procalcitonin levels compared with IL-6, TNF alpha and endotoxin levels early after thermal injury.

To determine the evolution and significance of circulating procalcitonin (ProCT), IL-6 TNF alpha and endotoxin levels early after thermal injury, we performed a prospective, single unit, longitudinal study. Forty burn patients with total body surface area (TBSA) > 30 per cent were studied, of whom 33 suffered an inhalation injury. Blood samples were taken on the day of admission, every 4 h during the first day and daily during the first week. All patients had increased ProCT and IL-6 levels without any proven infection. Endotoxin and TNF alpha levels remained very low or undetectable. ProCT and IL-levels correlated well with the severity of skin burn injury (respectively, p < 0.006 and p < 0.028, using the non-parametric Kruskal-Wallis test). ProCT levels are not associated with smoke inhalation. ProCT and IL6 are prognostic factors of mortality at the time of admission but less reliable than the clinical UBS (unit burn standard) score. Endotoxin and TNF alpha were undetectable, suggesting that the problem of the early gut bacterial translocation remains to be proven.

Adult↗
PubMed1980

The evolution of human longevity.

In the comparatively short history of human evolution man's lifespan has doubled, posing the question, by what means was this prolongation of life achieved. One line of thought correlates lifespan with oxygen consumption and energy generation, pointing out that small homeothersms which expend energy at a very high rate, are invariable short lived, while animals living more economically in terms of energy expenditure, like some heterotherms and large homeotherms, can attain greatly increased lifespan potentials. The correlation between lifespan and energy expenditure is generally valid, but some animals with low energy needs, notably tropical animals and some lethargic, inactive animals, do not live as long as expected on the basis of the theory. The present paper suggest that the aging process could be accelerated by hyperthermia and the longevity of some homeotherms, beside its connection with energy needs, could also be correlated with the evolution of temperature regulating mechanisms, resulting in more accurate thermal homeostasis. Man's uniquely capacious sweating mechanism, for example, may play a part in the attainment of his long life.

Aging↗