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PubMed1979

Dichlorophenylurea-resistant oxygen evolution in Chlorella after cerulenin treatment.

Fluorescence spectra at 77 K, oxygen evolution at 30 degrees C and delayed fluorescence at 25 degrees C were measured in Chlorella pyrenoidosa cultures with and without cerulenin and subsequent 3-(3,4-dichlorophenyl)-1,1-dimethyl-urea (DCMU) treatment, respectively. In pure algal cultures the oxygen evolution was inhibited by DCMU and the long-time component of fluorescence was highly influenced by DCMU, as expected. In contrast, both oxygen evolution and delayed fluorescence became DCMU-resistant in cerulenin-treated cultures. The DCMU-resistance is correlated with a change in the fatty acid distribution of the thylakoid membrane, which also leads to changes in the prompt fluorescence. Cerulenin appears to be a promising new tool of diagnostics for the hitherto unsatisfactorily understood processes of oxygen evolution in photosynthesizing organisms.

Antifungal Agents↗

PubMed1986

The effect of Cl- depletion and X- reconstitution on the oxygen-evolution rate, the yield of the multiline manganese EPR signal and EPR signal II in the isolated Photosystem-II complex.

The role of Cl- in photosynthetic O2 evolution has been investigated by measurement of the steady-state O2 rate and EPR of the electron donors responsible for the S2 multiline signal and Signal IIs upon Cl- depletion and substitution in Photosystem II membranes. Cl- removal has three effects upon the donor side of Photosystem II. (1) It abolishes O2 evolution reversibly, while decreasing the yield of the S2 multiline signal indicative of the manganese site of the O2-evolving complex in the S2 oxidation state. This decrease is brought about by (2) the reversible disconnection of the manganese complex from the reaction center; and by (3) deactivation of S1 centers having reduced primary acceptor QA to form SO centers having a reduced Signal IIs species. Reactivation of O2 evolution by anions confirms earlier work showing a requirement for a univalent anion of optimum charge density. The observed order of reactivation is Cl- greater than Br- approximately NO3- much greater than OH- approximately F-. Reactivation of the S2 multiline signal follows Cl- approximately Br- greater than NO3- approximately OH- greater than F-, in near correspondence with reactivation of O2-evolution rates. Cl- titrations of F- -inhibited samples reveal two binding sites for Cl- which differ in binding affinity by 11-fold. The higher-affinity site reactivates the S1----S2 light reaction, while the lower-affinity site reactivates the S3----S0 light reaction. The high affinity site is located within the O2-evolving complex at an undetermined site, while the lower-affinity site functions in coupling the reaction center photochemistry to the O2-evolving complex. The results are compared with Cl-/F- exchange equilibria for Mn3+ in solution. A model for the lower S-state transitions is presented in which specific oxidation state assignments are made for some of the donors and acceptors of Photosystem II.

Chlorides↗

PubMed1984

Karyotypic evolution in patients with acute myeloid leukemia.

Karyotypic evolution was found in 13 of 42 (31%) patients who were examined serially; if only those patients who were examined during successive stages of active leukemia were included, karyotypic evolution was revealed in 13 of 21 (62%). A further 6 patients showed multiple cytogenetic clones when leukemia was diagnosed. We did not find nonrandom chromosome involvement in the karyotypic changes, reported by others, notably trisomy #8. Our data for all patients who showed cytogenetic clones at some stage of their disease suggested that clones occurred with a higher incidence and arose earlier in patients with myeloblastic leukemia than in patients with myelomonocytic and monocytic leukemia. Patients showing karyotypic evolution tended to have longer than average survivals and to have had an abnormal karyotype when leukemia was diagnosed. The mode of preparation of hematologic samples, whether direct or cultured, has a bearing on karyotypic findings and could influence studies of karyotypic evolution.

Chromosome Aberrations↗

PubMed1989

Chromosomal evolution in the progression and metastasis of human malignant melanoma. A multiple lesion study.

In order to distinguish those chromosomal aberrations associated with tumorigenesis from those associated with tumor progression of malignant melanoma, chromosome analysis was performed on eight tumors derived from one patient. Three common marker chromosomes, a deletion of chromosome 1, a deletion of chromosome 9, and a translocation involving chromosomes 7 and 12, were identified in each tumor. The presence of common markers in these intrapatient tumors indicates the monoclonal origin of these tumors. Furthermore, the consistent and specific involvement of chromosome 9 in both interpatient and intrapatient studies suggests the crucial role that chromosome 9 plays during the development of human malignant melanoma. In addition to common markers, different overlapping markers including those involving chromosomes 2, 3, and 6, were also identified, suggesting that chromosomes 2, 3, and 6 are most likely associated with the progression, instead of the genesis, of the tumor. Finally, lesion-specific marker chromosomes were identified in each tumor indicating the nonrandom selection and modification of the metastatic process. The nature of chromosomal evolution among the eight tumors was clearly demonstrated by the retention and amplification of specific marker chromosomes, with the latter tumors containing more overlapping markers than the early tumors and the recurrence of identical markers in the different branches of evolution. One of the last three tumors obtained immediately before the death of the patient contained all the overlapping markers identified in other tumors, which may indicate that a plateau of chromosomal evolution of these tumors has been reached. These observations demonstrate a nonrandom or programmed chromosome evolution of human neoplasia that could be intrinsic to the aneuploid nature of neoplasia.

Chromosome Aberrations↗

PubMed1985

Studies on pentane evolution by rats treated with nifurtimox or benznidazole.

Sprague-Dawley male rats were treated with either 100 mg/kg Nifurtimox or Benznidazole p.o. and pentane evolution was measured at different periods of time. No significant increase in pentane evolution was observed in animals treated with Benznidazole during periods of time up to 10 h. In animals treated with Nifurtimox, a significant increase in pentane evolution was observed at 10 h but not at 3 or 6 h. The pentane evolution effect of Nifurtimox was compared to that of carbon tetrachloride. The latter was very intense up to 1 h and ceased thereafter. The possible participation of lipid peroxidation in the unwanted toxic side effects of Nifurtimox and Benznidazole is discussed.

Animals↗

PubMed2005

Intensity of malaria transmission and the evolution of drug resistance.

The intensity of malaria transmission varies both naturally and as a consequence of human public health intervention. The relationship between transmission intensity and the rate at which antimalarial drug resistance evolves affects the design of surveillance programmes, and the likely impact of malaria control programmes. Several theoretical studies have investigated this relationship and their key results are summarised and interpreted. The most important result is that transmission intensity does not directly affect the evolution of resistance. It exerts its influence through three clinical/epidemiological "mediators" (clonal multiplicity, the threat of infection, level of human immunity) which ultimately determine the dynamics of resistance via five "effector" variables: sexual recombination, intrahost dynamics, community drug use, proportion of malaria infections treated, and the number of parasites per host. We argue that the evolution of resistance is likely to be a two-stage process: mutations encoding drug tolerance preceding those encoding resistance. The evolution of drug tolerance is determined solely by the level of drug use in the community which is likely to have an extremely weak relationship with transmission intensity. The evolution of resistance is more complex and affected by all five effectors. The most likely scenarios are that resistance evolves faster in areas of high transmission if encoded by a single gene but if encoded by two or more genes it evolves fastest in areas of high or low transmission, with a minimum at intermediate levels of transmission.

Animals↗

PubMed2004

Enhancement of photosynthetic O2 evolution in Chlorella vulgaris under high light and increased CO2 concentration as a sign of acclimation to phosphate deficiency.

The photosynthetic oxygen evolution of Chlorella vulgaris (Beijer.) cells taken from phosphate-deficient (-P) and control cultures was measured during 8 days of culture growth. Under inorganic carbon concentration (50 microM) in the measuring cell suspension and irradiance (150 micromol m(-2) s(-1)), the same as during culture growth, there were no marked differences in the photosynthetic O2 evolution rate between the -P cells and the controls. The much slower growth of -P cultures indicated that the utilization of absorbed photosynthetically active radiation (PAR) in the CO2 assimilation and biomass production were in -P cells less efficient than in the controls. Alga cells under the phosphorus stress utilized more of the absorbed PAR in the nitrate reduction than the control cells. However, under conditions of more efficient CO2 supply (inorganic carbon concentration 150 microM, introducing of exogenous carbonic anhydrase to the measuring cell suspension) and under increased irradiance (500 micromol m(-2) s(-1)), the photosynthetic O2 evolution in -P cells reached a higher rate than in the controls. The results suggest that in -P cells the restricted CO2 availability limits the total photosynthetic process. But under conditions more favorable for the CO2 uptake and under high irradiance, the -P cells may reveal a higher photosynthetic oxygen evolution rate than the controls. It is concluded that an increased potential activity of the photosynthetic light energy absorption and conversion in the C. vulgaris cells from -P cultures is a sign of acclimation to phosphorus stress by a sun-type like adaptation response of the photosynthetic apparatus.

Carbonic Anhydrases↗

PubMed2004

Adaptation to the deleterious effects of antimicrobial drug resistance mutations by compensatory evolution.

Compensatory mutations, due to their ability to mask the deleterious effects of another mutation, are important for the adaptation and evolution of most organisms. Resistance to antibiotics, antivirals, antifungals, herbicides and insecticides is usually associated with a fitness cost. As a result of compensatory evolution, the initial fitness costs conferred by resistance mutations (or other deleterious mutations) can often be rapidly and efficiently reduced. Such compensatory evolution is potentially of importance for (i) the long-term persistence of drug resistance, (ii) reducing the rate of fitness loss associated with the accumulation of deleterious mutations in small asexual populations, and (iii) the evolution of complexity of cellular processes.

Amino Acid Sequence↗

PubMed2005

Evolution of the renal function is a better predictor of long-term survival than serum creatinine.

BACKGROUND: In recent years acute rejection has decreased to 10% to 20%. Therefore it is necessary to look for new endpoints in renal transplantation. Serum creatinine and changes in creatinine have been reported to be powerful predictors of long-term kidney transplant survival. Chronic renal allograft nephropathy is the primary cause of long-term graft failure but may appear at any stage in the evolution. METHODS: Data from 315 patients receiving cadaver donor renal transplants between February 1987 and March 2001 that functioned for 1 year were examined for the influence of demographic characteristics and transplant variables. Creatinine clearance was estimated using the Cockroft-Gault formula. Survival was assessed with the actuarial method. The multivariate analyses were performed using Cox proportional hazard models. RESULTS: The 10-year graft survival showed a relative risk of 2.5 in the univariate analysis when there was more than 10% decrease in renal function at 3 months compared with nadir values. When the decrease was more than 25% of creatinine clearance at the third month, during the evolution and serum creatinine at 3 months introduced in the multivariate model, the latter was not significant, while the other variables had a RR of 4.4 and 10, respectively. CONCLUSION: The evolution of renal function at 3 months and throughout the evolution were better predictors of graft failure than an isolated serum creatinine value.

Adult↗

PubMed2004

A phylogenetic approach to cultural evolution.

There has been a rapid increase in the use of phylogenetic methods to study the evolution of languages and culture. Languages fit a tree model of evolution well, at least in their basic vocabulary, challenging the view that blending, or admixture among neighbouring groups, was predominant in cultural history. Here, we argue that we can use language trees to test hypotheses about not only cultural history and diversification, but also bio-cultural adaptation. Phylogenetic comparative methods take account of the non-independence of cultures (Galton's problem), which can cause spurious statistical associations in comparative analyses. Advances in phylogenetic methods offer new possibilities for the analysis of cultural evolution, including estimating the rate of evolution and the direction of coevolutionary change of traits on the tree. They also enable phylogenetic uncertainty to be incorporated into the analyses, so that one does not have to treat phylogenetic trees as if they were known without error.

Journal Article↗

PubMed1972

Quantum accumulation in photosynthetic oxygen evolution.

Three independent methods have been used to determine the size of the quantum accumulation unit in green plant photosynthesis. This unit is defined as that group of pigment molecules within which quantal absorption acts must take place leading to the evolution of a single O(2) molecule. All three methods take advantage of the nonlinearity of oxygen yield with light dose at very low dosages. The experimental values of this unit size, based on an assumed model for the charge cooperation in O(2) evolution, ranging from 800 to 1600, suggest that there is either limited energy transfer between energy-trapping units or chemical cooperation among oxygen precursors formed in several neighboring energy-trapping units. Widely diffusible essential precursors to molecular oxygen are ruled out by these results. Inhibition studies show that O(2) evolution is blocked when 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) is added to chloroplasts after two preliminary flashes and before a third flash which would have yielded O(2) in the absence of DCMU. This experiment is interpreted as evidence that the site of DCMU inhibition is on the oxidizing side of system II. Pretreatment of chloroplasts with large concentrations of Tris, previously believed to destroy O(2) evolution by blocking an essential reaction in the electron chain between water and system II, may be alternately interpreted as promoting the dark reversal of the system II light-induced electron transfer.

Chloroplasts↗

PubMed1981

Evolution of the electrocardiogram in young dogs with congenital heart disease leading to right ventricular hypertrophy.

In 18 pups obtained from a breeding colony established for investigation of hereditary heart disease, ECG's were recorded shortly after birth. The ECG's, as well as clinical examinations, were repeated weekly in pups surviving the first week of life. The QRS modal axis was constructed in the frontal, transverse and sagittal planes. Cardiac catheterization was performed on all pups reaching the age of 8 to 12 weeks. VCG's were taken on selected pups. All dogs were necropsied terminally. In pups with severe pulmonic stenosis a pathological right ventricular hypertrophy was recognized immediately after birth. No evolution to a left ventricular dominance occurred in the serial tracings. Pups with milder grades of right ventricular outflow obstruction showed a normal evolution pattern or some minor deviations from the normal QRS complex evolution. In pups with patent ductus arteriosus (PDA) and left-to-right shunt, there was no difference from the normal ECG evolution within the first 12 weeks of life, except for some increase in amplitude. Two cases of PDA and right-to-left shunt were not different from the "physiologic right ventricular hypertrophy" at birth, but developed a severe right ventricular hypertrophy pattern within the first 12 weeks of life without any clinical signs of a left-to-right shunting within the period.

Animals↗

PubMed2004

Hidden chromosomal aberrations are rare in primary myelodysplastic syndromes with evolution to acute myeloid leukaemia and normal cytogenetics.

In myelodysplastic syndromes (MDS) a normal karyotype by cytogenetic analysis (CA) corresponds to a low cytogenetic risk for acute myeloid leukaemia (AML) evolution, a subset of patients however develops AML. We evaluated the use of interphase fluorescence in situ hybridisation (I-FISH) in 31 patients with evolution from primary MDS to AML and a normal CA at all stages of disease. Monosomy 7 was found in 4/31 cases, one patient had a terminal deletion 5q, each after AML evolution. The low frequency and unclear prognostic value of I-FISH anomalies in MDS related AML suggests that these alterations play a minor role for AML evolution.

Acute Disease↗

PubMed1998

Determinants of Life-history Evolution in Nematodes.

What are the determinants of parasite life-history evolution? Does life-history evolution of parasitic species differ from their free-living relatives? How and why do host and parasite life-history traits covary? Here, Serge Morand and Gabriele Sorci use recent comparative studies to investigate life-history evolution in nematodes which present both parasitic and free-living groups. Application of life-history theory to nematodes suggests that the conventional wisdom concerning the high fecundity of parasitic species could simply be the result of the larger body size of the latter when compared with free-living forms. The authors also emphasize, with the use of examples, that in most cases parasite life-history evolution depends on host features.

Journal Article↗

PubMed2002

[Wilson's disease. Clinical presentation, treatment and evolution in 21 cases].

PURPOSE: Wilson's disease is characterized by neuropsychiatric symptoms with frequent extrapyramidal and intellectual presentations. They have an insidious evolution that leads to a late diagnosis and less therapeutic effectiveness in the advanced forms. METHODS: We report 21 cases of Wilson's disease with neurological complications, emphasizing clinical semiology, diagnostic means and problems of the therapeutics in our country. RESULTS: The average age at the beginning of the disease was 17.6 years, with a female prevalence (8/13). The signs at first were mostly all neurological (71.4%), then psychiatric (19%) or hepatic (19%). The most common neurological signs were dystonia of members (81%), dysarthria (76%), tremors (76%) or disorders of motoricity (71.4%). Sometimes there were sialorrhea or disorders of the handwriting. The Kayser-Fleischer ring was present in 19 patients. Eighteen patients had clinical and/or biological hepatic involvement. The diagnosis was confirmed by biochemical examinations, which found a low rate of copper in blood, a sinking rate of ceruloplasmin and a very high rate of urinary copper. The cerebral computer tomography shows a cortical and/or subcortical atrophy (37%), and/or a low density of the central grey cores (35%). The treatment was based on D-penicillamine and/or zinc sulfate, according to the availability of the drugs. The evolution was favourable among 18 patients (85%) and not good in 42.8% of the cases. Six of the first patients had poor evolution after many years of follow-up. Finally, only 12 patients (57%) had a very good outcome. The family investigation made among 17 patients revealed 13 family cases. The only predictive factor of a poor evolution was the therapeutic noncompliance (P = 0.006). CONCLUSIONS: The neurological presentations are traditional during the Wilson's disease, but are often ignored. We must suspect the disease in children when faced with disorders of handwriting or school failures and in the adult, when faced with neurological symptoms in a patient having a hepatic disease. We must not hesitate to consider it even given purely psychiatric signs, and we had better know to seek the neurological ones.

Adolescent↗

PubMed1999

[Treatment of rheumatoid polyarthritis: evolution of concepts and strategies].

INTRODUCTION: The treatment of rheumatoid arthritis includes non-steroid anti-inflammatory drugs (NSAID), low-dose steroids and drugs which modify the evolution of the disease (disease modifying anti-rheumatic drugs, [DMARD]). In the last few years, the long-term efficiency of the recommended treatment strategies in rheumatoid arthritis has been a matter of debate and their basic assumptions have been challenged. Numerous studies were undertaken to settle the question. They tried to delineate the rules for an optimal use of current drugs and other therapeutic means. CURRENT KNOWLEDGE AND KEY POINTS: Rheumatoid arthritis is a crippling disease. It decreases life expectancy and irreversible bone and joint damage may develop even in the first months of evolution. The sooner the prescription of DMARD, the higher the frequency and quality of rheumatoid arthritis improvement and, in the long-term, the lesser the functional impairment. Low dose steroids, when administered early, can slow down the development of radiologic lesions. Some of their effects are thus closer to those of DMARD than to those of symptomatic treatment. NSAID are at least as equally dangerous as DMARD and possibly more so in terms of the potential number of severe side effects. The combination of several DMARD does not increase their overall toxicity. An evaluation of the most efficient combinations and of the clinical situations in which combinations show promise of improved results is in progress. FUTURE PROSPECTS AND PROJECTS: At present, the tendency is to treat early and intensively, in order to obtain complete remission, improve evolution and reduce functional impairment. This strategy requires early diagnosis and early evaluation of prognosis of rheumatoid arthritis. Rheumatoid arthritis with benign evolution would not warrant intensive treatment. Studies are in progress to evaluate the prognostic factors in early rheumatoid arthritis that would enable us to adapt the strength of initial treatment to the disease's putative severity.

Adrenal Cortex Hormones↗

PubMed1997

Machines for automated evolution experiments in vitro based on the serial-transfer concept.

Two machine setups for automated evolution experiments in vitro are described. Both machines enable the monitoring of growing populations of RNA or DNA molecules in real time using high-sensitivity glass fiber laser fluorimeters and an automated sample handling facility for volumes in the microliter range. Growth conditions are kept constant by means of the serial-transfer technique, that is, the successive transfer of a small fraction of a growing population into a fresh solution containing no individuals prior to the transfer. The serial transfer technique was modified to work with large populations and constant growth conditions. In the single-channel evolution machine isothermal amplification reactions (Qbeta-system, 3SR, NASBA, SDA) are monitored successively in single test tubes. This machine is particularly well suited for the investigation of optimal adaptation to altered environmental conditions, as is experimentally demonstrated in the evolution of an RNA quasi-species using ribonuclease A as the selection pressure. The new variant of RNA appeared very rapidly (within approximately 80 generations) without stable intermediates, and it was selected by steadily increasing the RNaseA concentration during the serial-transfer experiment. The other machine, which is described in the second part of this article, is a consequent extension of the single-channel machine, and was designed to allow the multichannel detection of up to 960 samples simultaneously. Thus, high-throughput screening can be applied to evolution experiments. In addition to monitoring isothermal amplification reactions, it is also possible to follow PCR amplifications through thin plastic foils. Initial experiments have demonstrated the suitability of the apparatus for uniformly processing samples and for performing thermocycling.

Base Sequence↗

PubMed1997

The role of peptide modules in protein evolution.

Protein evolution shows interesting strategies to be used in protein design. During evolution the creation of new proteins has been accomplished by combining different peptide modules, i.e. evolutionary successful stable folding units. Thereby, the evolution of proteins has been greatly enhanced. Today this mechanism of recombining optimized building blocks to design new proteins has been introduced into applied molecular evolution.

Journal Article↗