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Results for “systematic evolution”

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PubMed2000

Toward a new synthesis: major evolutionary trends in the angiosperm fossil record.

Angiosperm paleobotany has widened its horizons, incorporated new techniques, developed new databases, and accepted new questions that can now focus on the evolution of the group. The fossil record of early flowering plants is now playing an active role in addressing questions of angiosperm phylogeny, angiosperm origins, and angiosperm radiations. Three basic nodes of angiosperm radiations are identified: (i) the closed carpel and showy radially symmetrical flower, (ii) the bilateral flower, and (iii) fleshy fruits and nutritious nuts and seeds. These are all coevolutionary events and spread out through time during angiosperm evolution. The proposal is made that the genetics of the angiosperms pressured the evolution of the group toward reproductive systems that favored outcrossing. This resulted in the strongest selection in the angiosperms being directed toward the flower, fruits, and seeds. That is why these organs often provide the best systematic characters for the group.

Journal Article↗

PubMed2000

Imaging changes in the pancreas in cystic fibrosis: a retrospective evaluation of 55 cases seen over a period of 9 years.

BACKGROUND: Pathologic changes of the pancreas have been observed as early as the recognition of the disease termed initially "cystic fibrosis of the pancreas". Atrophy of the gland and its fatty infiltration were considered as usual features. The aim of this study was to follow-up the evolution of cystic fibrosis pancreas and to define its successive stages in correlation with the clinical, biochemical, and imaging findings. METHODS: Fifty-five patients were followed up during 9 years. The patients' genetic backgrounds were systematically performed. Blood lipase levels were analyzed systematically at each consultation of the patients and in the event of bouts of abdominal pains. Imaging using mainly echograms and tomodensitometric scans were regularly performed: echograms every 6 months, and tomodensitometric scans every 1 to 2 years. Magnetic resonance imaging was performed in four patients. RESULTS: Five groups of patients were identified on the basis of tomodensitometric scan findings: normal pancreas (n = 4), incomplete lipomatosis of the pancreas (n = 9), complete lipomatosis of the pancreas (n = 23), cystic pancreas (n = 5), macrocystic pancreas (n = 1), atrophic pancreas (n = 13). Pancreas exocrine function was not correlated with findings. Forty episodes of pancreatitis were observed in seven patients. They had bouts of abdominal pain and elevation of lipase levels. Five of these patients were composite heterozygotes (D508/other). Incomplete lipomatosis represents an intermediate stage leading toward complete lipomatosis or toward atrophy after pancreatitis. CONCLUSIONS: Studies of pancreatic function should be performed routinely in cystic fibrosis, especially in pancreatic sufficiency or in patients with normal pancreas images. Acute pancreatitis should be diagnosed and properly identified to be differentiated from other acute abdominal syndromes occurring in cystic fibrosis.

Adolescent↗

PubMed1989

Aging of the diaphragm: a CT study.

To determine the normal morphologic evolution of the diaphragm with aging and to correlate age-related changes with other indicators of physical condition--such as skeletal muscle status, obesity, presence of pulmonary emphysema, and presence of esophageal hiatus hernia--a systematic morphometric and morphologic evaluation of computed tomographic studies of 120 patients from the 3d to 8th decades of life was undertaken. Diaphragm muscle thickness did not change significantly with increasing age. Diaphragmatic defects and pseudotumors, nonexistent in the 3d and 4th decades, increased in number and severity to affect 56% of the patients in the 7th and 8th decades. Neither the status of the skeletal muscle nor the presence of obesity correlated with age or with the presence of diaphragmatic defects. Eighty-four percent of the patients with emphysematous changes demonstrated diaphragmatic defects; thus, a strong association with emphysema was observed. If emphysematous patients are excluded, defects were more common in women. The esophageal hiatus width was found to increase with age.

Adult↗

PubMed1998

Advances in laparoscopic surgery.

After a brief account of the origins of laparoscopy and of its development into an interventional technique thanks to technical improvement, the author gives a dynamic state of the art in laparoscopic surgery, beginning with a description of his original classification method for laparoscopic procedures according to their level of use. Before tackling the highly controversial issue of laparoscopic surgery for cancer, he reviews in detail the various operations successfully performed by laparoscopy for the treatment of nonmalignant abdominal disorders and acute syndromes, all the while checking their results against those obtained with their open counterparts. As the various procedures are described, the interest of the laparoscopic approach becomes clearly visible, based on the excellent view of the operative field that allows diagnostic accuracy, thus avoiding unnecessary operations, and precise dissection with minimal damage. However, the laparoscopic approach is highly dependent on the surgeon's proficiency, itself depending on experience and therefore on the frequency of occurrence of the disorder, and on the progress in and availability of adequate equipments. The last chapter looks into the future of this ever-expanding approach and defines two great trends in its evolution, one accessible to the individual surgeon, the gradual adaptation of open procedures into laparoscopic ones, the other at the institutional level, in view of the huge financial support involved if high technologies are to be systematically integrated in this new surgery. What will the future be like?

Digestive System Diseases↗

PubMed1999

Abnormal tenascin expression in murine autosomal recessive polycystic kidneys.

The mechanisms responsible for renal cyst formation in congenital polycystic kidney disease (PKD) remain unknown. Changes in extracellular matrix (ECM) are regarded as an important pathogenic factor in PKD. Tenascin, an ECM glycoprotein implicated in abnormal growth in adult organs, has not been systematically evaluated in PKD. In this study, tenascin expression was studied by immunohistochemistry in the autosomal recessive polycystic kidneys of C57BL/6J (cpk/cpk) mice. Scanning electron microscopy was performed to determine the cyst types and their temporal evolution, and to establish correlations with the immunohistochemistry observations. Cystic lesions evolved in three main stages. Initially, the cysts appeared as segmental dilatations of both proximal and collecting ducts. In the second stage, the collecting duct cysts (CDCs) underwent rapid growth that led to the destruction of all other kidney elements. In the final stage, the CDCs reached their maximum size and the PKD mice died. Normal differentiated principal cells and three types of intercalated cells were present in the CDC epithelium. In all three stages an intense tenascin expression was detected selectively in the basement membranes of the cysts. In the last stage, an intense tenascin immunoreactivity was also observed in the interstitial fibrotic tissue. The abnormal presence of tenascin in the basement membranes of the cysts suggests that this glycoprotein is implicated in the pathogenesis of the cysts, possibly by stimulating cell proliferation.

Age Factors↗

PubMed1994

[Current status of immunization in the Armed Forces: need of continuous adaptation of vaccinations against cerebrospinal meningitis, typhoid and hepatitis A].

The history of military medicine has always been closely linked with that of vaccinations. Doctors of Armed Forces, doctors of collectivities, have contributed to vaccination progresses in large amounts. But evolutions are often rapid here: epidemiological modifications, improvements in the existing vaccines or creation of new vaccines, diversification of military specificities. Three recent modifications in the vaccination schedule of the Armed Forces show this necessary adaptation: systematization of the meningococcal A+C vaccination during the incorporation, because of the modification of the disease's epidemiological profile; increase of the frequency in serogroup C with a mortality increase (9 cases of death out of 10 observed between 1991 and 1992); cancellation of antityphoid vaccination for recruits serving in home country. Indeed the disease has become rare in France, and this is often due to imported cases (3 cases in the Armed Forces in 1992); introduction in 1994 of vaccination against viral hepatitis A, systematic under the age of 25 years and after a serological selection above for servicemen having to serve overseas or for outside operations. These 3 examples show the necessity to have updated and adaptable vaccination schedules.

Bacterial Vaccines↗

PubMed1993

[Realities of immunizations in the armed forces: necessity of continued adaptation of vaccinations against cerebrospinal meningitis, typhoid and hepatitis A].

The history of military medicine has always been closely linked with that of vaccinations. Doctors of Armed Forces, doctors of collectivities, have contributed to vaccination progresses in large amounts. But evolutions are often rapid here: epidemiological modifications, improvements in the existing vaccines or creation of new vaccines, diversification of military specificities. Three recent modifications in the vaccination schedule of the Armed Forces show this necessary adaptation: Systematization of the meningococcal A + C vaccination during the incorporation, because of the modification of the disease's epidemiological profile: increase of the frequency in serogroup C with a mortality increase (9 cases of death out of 10 observed between 1991 and 1992). Cancellation of antityphoïd vaccination for recruits serving in home country. Indeed the disease has become rare in France, and this is often due to imported cases (3 cases in the Armed Forces in 1992). Introduction in 1994 of vaccination against viral hepatitis A, systematic under the age of 25 years and after a serological selection above for servicemen having to serve overseas or for outside operations. These 3 examples show the necessity to have updated and adaptable vaccination schedules.

Bacterial Vaccines↗

PubMed1976

[Acute consumption coagulopathies. 120 cases].

Consumption coagulopathy is frequently observed in a resuscitation department. 120 cases of various etiologies are reviewed: complications of pregnancy (61 cases), infections (23 cases) or various stresses: acute hemolysis, shock, severe hepatic failure, intoxications, acidosis, heat-stroke... Consumption coagulopathy is intricated with the general stress which induces it, and with the visceral lesions induced by the stress and which can be aggravated by the consumption coagulopathy. The state of shock is observed in 76% of the cases, the haemorrhagic syndrome in 73%. Acute hemolysis and the clinical signs evocative of disseminated intravascular coagulation (cutaneous signs) are more rare. Following the initial manifestations, visceral complications may develop: renal, hepatic, respiratory, neurological, digestive. The evolution of the biology must be carefully studied. The diagnosis is made on both clinical and biological data. Etiological and pathophysiological treatment should be carried out. In our series, controlled and adapted heparin therapy was given systematically.

Disseminated Intravascular Coagulation↗

PubMed2024

Multisubstrate specificity shaped the complex evolution of the aminotransferase family across the tree of life.

Aminotransferases (ATs) are an ancient enzyme family that play central roles in core nitrogen metabolism, essential to all organisms. However, many of the AT enzyme functions remain poorly defined, limiting our fundamental understanding of the nitrogen metabolic networks that exist in different organisms. Here, we traced the deep evolutionary history of the AT family by analyzing AT enzymes from 90 species spanning the tree of life (ToL). We found that each organism has maintained a relatively small and constant number of ATs. Mapping the distribution of ATs across the ToL uncovered that many essential AT reactions are carried out by taxon-specific AT enzymes due to wide-spread nonorthologous gene displacements. This complex evolutionary history explains the difficulty of homology-based AT functional prediction. Biochemical characterization of diverse aromatic ATs further revealed their broad substrate specificity, unlike other core metabolic enzymes that evolved to catalyze specific reactions today. Interestingly, however, we found that these AT enzymes that diverged over billion years share common signatures of multisubstrate specificity by employing different nonconserved active site residues. These findings illustrate that AT family enzymes had leveraged their inherent substrate promiscuity to maintain a small yet distinct set of multifunctional AT enzymes in different taxa. This evolutionary history of versatile ATs likely contributed to the establishment of robust and diverse nitrogen metabolic networks that exist throughout the ToL. The study provides a critical foundation to systematically determine diverse AT functions and underlying nitrogen metabolic networks across the ToL.

Substrate Specificity↗

PubMedDate not supplied

Do all colorectal carcinomas arise in preexisting adenomas?

In this article, the underlying nature of the adenoma is defined and evidence in support of the adenoma-carcinoma sequence is presented. Emphasis is placed on recent findings from the field of molecular biology which fortify the concept of the adenoma as a step in the evolution of large bowel cancer. Despite the considerable body of indirect evidence in support of the adenoma-carcinoma sequence, the de novo theory still has some support. Although differences between the de novo and adenoma carcinoma concept are largely semantic, the fact that infiltrating carcinoma can arise within small, flat foci of severely dysplastic epithelium (indistinguishable from carcinoma in situ) may be of considerable clinical importance. Other routes of morphogenesis exist also, but these make a relatively small contribution to the overall incidence of colorectal cancer. Even if it is accepted that the majority of colorectal cancers develop in a preexisting adenoma, the systematic removal of adenomas would pose a number of practical difficulties. First, adenomas are extremely common, particularly in populations at high risk of colorectal cancer. A second factor is the recently recognized existence of flat or depressed adenomas which may be small and difficult to visualize endoscopically. A simple screening program based on our knowledge of the evolution of colorectal cancer is outlined.

Adenoma↗

PubMed1999

Mitochondrial DNA phylogeny and the evolution of host-plant use in palearctic Chrysolina (Coleoptera, Chrysomelidae) leaf beetles.

The genus Chrysolina consists of specialized phytophagous leaf-beetles (Coleoptera, Chrysomelidae) with feed on several plant families. There is no explicit phylogenetic hypothesis available for this genus, which includes 65 subgenera and more than 400 species with a wide distribution. We obtained 839-bp sequence data from the 16S rDNA and cytochrome oxidase subunit I (COI) mitochondrial genes. Thirty Chrysolina taxa representing eight host-plant affiliations, two species of the closely related genus Oreina, and two outgroups were sampled. These data sets were used separately and combined to obtain the mitochondrial cladogram of the group using maximum-parsimony and maximum-likelihood criteria. The results were compared to current proposals for Chrysolina systematics that are based on morphological, ecological, and karyological data. The trees obtained were in the most part congruent with the proposed ancestral association of Chrysolina to Lamiaceae based on chromosome number in several lineages. A minimum of five host-plant switches from the ancestral state inferred at the family level and two at the subclass level suggests the absence of parallel evolution of beetles and their host plants. Another switch leading to oligophagy at the family level was deduced to have occurred in the lineage of the subgenus Chrysolina s.str.

Animals↗

PubMed1994

Postnatal mental illness: a transcultural perspective.

The three main conditions that are associated with childbirth are the maternity blues, postnatal depression and post-partum psychosis. The prevalence of the blues, which are mild, transient and very common disturbances of postnatal mood, does not appear in a major way to be related to environmental, social or cultural factors. Postnatal depression, which has a predominantly psychosocial etiology, surprisingly does not appear to vary in incidence across different cultures in the few studies reported that permit direct comparisons. There is also no good evidence for or against the theory that postnatal depression is partly the consequence of the customs and rituals that traditionally mark the transition to parenthood being stripped away in developed Western societies. However, the lack of relevant research and limitations of method severely restrict any conclusions that can be drawn. There is much firmer evidence for a consistent incidence of post-partum psychosis across cultural and ethnic divides; this observation, together with clinical data and historical evidence of an unchanging incidence rate during the past 150 years, points to a primarily endogenous etiology for the psychoses, which may be triggered by the physiology of childbirth. The transcultural approach to postnatal psychiatric disorders provides a unique opportunity not only to test hypotheses about social and cultural contributions to the etiology of psychotic and non-psychotic reactions to childbirth, but also an opportunity to study the ways in which social factors can influence the evolution of psychopathology. It is also possible that in some cultures the family and social milieu may play a major part in buffering infants from the adverse effects of maternal postnatal illness, but the evidence is anecdotal. Systematic research across cultures will lead to better recognition of maternal illness as well as to better prevention and management.

Cross-Cultural Comparison↗

PubMed2003

Efficient multipoint mapping: making use of dominant repulsion-phase markers.

The paper is devoted to the problem of multipoint gene ordering with a particular focus on "dominance" complication that acts differently in conditions of coupling-phase and repulsion-phase markers. To solve the problem we split the dataset into two complementary subsets each containing shared codominant markers and dominant markers in the coupling-phase only. Multilocus ordering in the proposed algorithm is based on pairwise recombination frequencies and using the well-known travelling salesman problem (TSP) formalization. To obtain accurate results, we developed a multiphase algorithm that includes synchronized-marker ordering of two subsets assisted by re-sampling-based map verification, combining the resulting maps into an integrated map followed by verification of the integrated map. A new synchronized Evolution-Strategy discrete optimization algorithm was developed here for the proposed multilocus ordering approach in which common codominant markers facilitate stabilization of the marker order of the two complementary maps. High performance of the employed algorithm allows systematic treatment for the problem of verification of the obtained multilocus orders, based on computing-intensive bootstrap and jackknife technologies for detection and removing unreliable marker scores. The efficiency of the proposed algorithm was demonstrated on simulated and real data.

Algorithms↗

PubMed1985

Maturation of contralateral brain-stem responses in preterm infants.

Average auditory brain-stem responses (ABRs) evoked by left and right ear stimulation of varying intensities were recorded from ipsilateral and contralateral scalp placements in human neonates. Subjects included pre-term infants, healthy full-term infants and high risk, full-term infants. Pre-term infants were classified into 4 age groups ranging from 29 to 41 weeks post-conceptional age (PCA). Significant ipsilateral/contralateral differences were observed. Further, this effect was highly dependent upon age. The youngest pre-term infants were devoid of contralateral activity despite robust ipsilateral responses. The emergence and evolution of the contralateral wave form could readily be visualized from 31 to 37 weeks PCA. The contralateral response was uninfluenced by stimulus intensity but appeared to be related to the amplitude of the ipsilateral response. No systematic ear differences were noted. Pre-term infants tested between 38 and 41 weeks PCA (term equivalence) showed some persisting immaturity in terms of the ABR. Healthy and sick full-term infants were indistinguishable with respect to ipsilateral or contralateral potentials. On the other hand, very ill 6-week-old infants showed specific contralateral abnormalities.

Brain Stem↗

PubMed2005

Genomic organization of the sheep TRG1@ locus and comparative analyses of Bovidae and human variable genes.

gammadelta T cells commonly account for 0.5%-5% of human (gammadelta low species) circulating T cells, whereas they are very common in chickens, and they may account for >70% of peripheral cells in ruminants (gammadelta high species). We have previously reported the ovine TRG2@ locus structure, the first complete physical map of any ruminant animal TCR locus. Here we determined the TRG1@ locus organization in sheep, reported all variable (V) gamma gene segments in their germline configuration and included human and cattle sequences in a three species comparison. The TRG1@ locus spans about 140 kb and consists of three clusters named TRG5, TRG3, and TRG1 according to the constant (C) genes. The predicted tertiary structure of cattle and sheep V proteins showed a remarkably high degree of conservation between the experimentally determined human Vgamma9 and the proteins belonging to TRG5 Vgamma subgroup. However systematic comparison of primary and tertiary structure highligthed that in Bovidae the overall conformation of the gammadelta TCR, is more similar to the Fab fragment of an antibody than any TCR heterodimer. Phylogenetic analysis showed that the evolution of cattle and sheep V genes is related to the rearrangement process of V segments with the relevant C, and consequentely to the appartenence of the V genes to a given cluster. The TRG cluster evolution in cattle and sheep pointed out the existence of a TRG5 ancient cluster and the occurrence of duplications of its minimal structural scheme of one V, two joining (J), and one C.

Animals↗

PubMed1997

The heterogeneous course of schizophrenia.

Findings on the course and outcome of schizophrenia, the limitations of Kraepelin's opinion, and data supporting a continuum hypothesis of endogenous psychoses are presented. The European long-term investigations, the Zürich, Lausanne and Bonn studies are consistent with the view that diagnoses must be made independently of outcome; nearly a quarter show full psychopathological and 56% a social remission. Several factors are relevant to the long-term course and outcome. In the Bonn Study, 43% of subjects showed long-term remission, with only a mild deficit state ('pure defect') consisting of dynamic and cognitive basic symptoms, and 35% revealed characteristic schizophrenic residues. Eighty-seven per cent were living at home permanently at the most recent follow-up; 56% were socially recovered, i.e., fully employed, yet only 38.6% were at their previous occupational level. Twelve course types could be differentiated and were ranked according to social remission rate. The results led to a revision of classical descriptions of an incessant progression of schizophrenia. The outcome is largely independent of the duration of illness; there is no increasing deterioration in the later decades of the disease, often showing a trend toward improvement (the 'second, positive bend'), even 20-40 years after onset. According to Zubin, the results of the European long-term studies and the Vermont Study have revolutionized our knowledge about schizophrenia and emancipated it from the yoke of inevitable chronicity. The findings of the Bonn Study, the first systematic study of prodromes, and of the prospective basic symptom-oriented study on the early diagnosis of schizophrenia led, in parallel with the gradual development of the basic symptom concept, to a new view of the evolution of schizophrenia.

Disease Progression↗

PubMed2004

The challenge of using virtual reality in telerehabilitation.

Continuing advances in virtual reality (VR) technology along with concomitant system cost reductions have supported the development of more useful and accessible VR systems that can uniquely target a wide range of physical, psychological, and cognitive rehabilitation concerns and research questions. VR offers the potential to deliver systematic human testing, training, and treatment environments that allow for the precise control of complex dynamic three-dimensional stimulus presentations, within which sophisticated interaction, behavioral tracking, and performance recording is possible. The next step in this evolution will allow for Internet accessibility to libraries of VR scenarios as a likely form of distribution and use. VR applications that are Internet deliverable could open up new possibilities for home-based therapy and rehabilitation. If executed thoughtfully, they could increase client involvement, enhance outcomes and reduce costs. However, before this vision can be achieved, a number of significant challenges will need to be addressed and solved. This article will first present three fictional case vignettes that illustrate the ways that VR telerehabilitation might be implemented with varying degrees of success in the future. We then describe a system that is currently being used to deliver virtual worlds over the Internet for training safety skills to children with learning disabilities. From these illustrative fictional and reality-based applications, we will then briefly discuss the technical, practical, and user-based challenges for implementing VR telerehabilitation, along with views regarding the future of this emerging clinical application.

Adult↗

PubMed1994

Genetic analysis of systematic mitochondrial heteroplasmy in rabbits.

One unusual property of rabbit mitochondrial DNA (mtDNA) is the existence of repeated 153-bp motifs in the vicinity of the replication origin of its H strand. Furthermore, every individual is heteroplasmic: it carries mtDNA molecules with a variable number of repeats. A systematic study of 8 females and their progeny has been devised to analyze mtDNA transmission through generations. The results suggest that three mechanisms are acting simultaneously. (1) Genetic drift in the germ line is revealed by the evolution of heteroplasmy when two major molecular forms are present in a female. (2) A high mutation rate (around 10(-2) per animal generation) generating molecular diversity, by deletion and addition of repeated units, is required to explain the observation of heteroplasmy in every individual. Moreover, the rates of mutation from the most frequent type to the other types are unequal. The deletion of one unit is more frequent than a deletion of two units, which is in turn more frequent than a deletion of three. (3) Selection for shorter molecules in somatic cells is probable. The frequency distribution of mtDNA types depends on the organ analyzed (kidney-spleen and liver vs. gonads).

Animals↗