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At least 451 records · Page 25Linked to original sources
PubMed2000

Molecular biology of multiple organ dysfunction syndrome: injury, adaptation, and apoptosis.

Injury will equal or surpass communicable disease in the year 2020 as the number one cause of lost disability-adjusted life-years worldwide. The major cause of "late death" after trauma is organ dysfunction, commonly as a complication of shock or sepsis. The pathophysiology of injury-induced organ dysfunction is poorly characterized but has been linked to systemic inflammation as a result of infection (either obvious or occult) or massive tissue injury (systemic inflammatory response syndrome, SIRS). Subsequent complications of organ dysfunction, including death, may also stem from immunosuppression characteristic of what has been called the counter-regulatory anti-inflammatory response syndrome (CARS). At the cellular level, injurious stimuli trigger adaptive stress responses that include changes in gene expression. Multiple organ dysfunction syndrome (MODS) is the summation of these stress responses to severe systemic injury, integrated at the cellular, organ, and host levels. We hypothesize that a complete understanding at the molecular level of the stress responses induced by injury will aid in the development of therapeutic strategies for treating MODS in the critically ill surgical patient. This paper reviews recent data from our Cellular Injury and Adaptation Laboratory relevant to our understanding of MODS pathophysiology, particularly as it relates to stress-induced cell death by apoptosis. Our data suggest that inhibition of stress-induced apoptosis may improve survival after severe injury.

Adaptation, Biological↗
PubMed1988

Estimating ultrasonic parameters of biological tissue by adaptive filtering technique.

Diagnostic ultrasonic imaging is widely used as a non-invasive technique for examining the body. However, the resolution of images still does not meet the order of the wavelength, and only a part of the information on tissue characteristics contained in reflected signals is used. In this paper we propose a method for estimating two tissue parameters; i.e., the reflection coefficient and attenuation coefficient from the reflected ultrasound for the purpose of improving the resolution of ultrasonic images and obtaining information on tissue characterization. The reflection coefficient is estimated by a deconvolution technique using a Kalman filter, taking into account the distortion of the propagating pulse due to frequency-dependent attenuation. The attenuation is estimated by adaptive processing based upon the criterion function calculated using estimates of the reflection coefficient. Simulated signals are used to investigate the ability of this method. Additionally, experimental results for reflected signals from a human liver show that the method is applicable to clinical cases.

Filtration↗
PubMed1997

Hierarchical organization of biological systems and the structure of adaptation in evolution and tumorigenesis.

Biological systems are structurally organized according to patterns repeated at each hierarchical level. Complex units are composed of so-called interactors, systems that by cooperative interaction maintain the structure of the complex unit. Interactors are composed of large numbers of assemblies of complex units of a limited number of types of a lower hierarchical level. Thus, macromolecules, cells, organisms and ecological communities should be defined as complex units, and cellular organelles, organs and oligospecies populations as the interactors between those units. The similarity of organization at each level should make it possible to describe patterns of structure at one level and apply it to organization at another level. This was tested for the structural aspects of adaptation as viewed in a pathobiological context. Adaptation is then viewed as the result of stress seen at the level of the interactors or at the level of the lower complex units related to the type of stress. Subsequently, this structure of adaptation was applied to adaptation in biological evolution and tumorigenesis, which has led to the conclusion that stress is a driving force for both and that an increase in number of organisms or cells may precede heritable changes or mutations, respectively.

Adaptation, Physiological↗
PubMed1998

Biological affinities and adaptations of Bronze Age Bactrians: III. An initial craniometric assessment.

Discovery of a previously unknown Bronze Age civilization (Oxus Civilization) centered on the oases of Central Asia immediately raised questions concerning the origin and interregional impacts of this civilization. Fifteen craniometric variables from 12 Bronze Age samples--encompassing 544 adults from Central Asia, Iran, the Indus Valley, and Anatolia--are compared to test which, if any, of the current hypotheses offered by archaeologists are best supported by the pattern of phenetic affinities possessed by the Oxus Civilization inhabitants of the north Bactrian oasis. Craniometric differences between samples are compared with Mahalanobis generalized distance, and patterns of phenetic affinity are assessed with two types of cluster analysis (WPGMA, neighbor-joining method), multidimensional scaling, and principal coordinates analysis. Results obtained by this analysis indicate that current hypotheses for both the origin and interregional impacts of Oxus Civilization populations are incomplete.

Adult↗
PubMed1999

Biological affinities and adaptations of Bronze Age Bactrians: IV. A craniometric investigation of Bactrian origins.

Discovery of a previously unknown Bronze Age civilization (Oxus civilization) centered on the oases of Central Asia revealed the presence of large, preplanned urban centers immediately above sterile soil. Given the absence of local antecedents, the sudden appearance and proliferation of these Oxus civilization urban centers in the oases of Bactria and Margiana immediately raised the issue of where the inhabitants of these urban centers came from. Three hypotheses have been offered by archaeologists to account for the origins of Oxus civilization populations. These include the early influence model, the late colonization model, and the trichotomy model. Eleven craniometric variables from 12 Aeneolithic and Bronze Age samples, encompassing 657 adults from Central Asia, Iran, and the Indus Valley, are compared to test which if any of these hypotheses are supported by the pattern of phenetic affinities possessed by the Oxus civilization inhabitants of the north Bactrian oasis. Craniometric differences between samples are compared with Mahalanobis generalized distance (d2), and patterns of phenetic affinity are assessed with two types of cluster analysis (WPGMA, neighbor-joining method), multidimensional scaling, and principal coordinates analysis. Results of this analysis provide no support for either the late colonization model or the trichotomy model but do offer some support for the early influence model. Nevertheless, it is clear that the early influence model fails to account for a shift in interregional contacts, perhaps from western China to the north around 2000 BC, that appears to have played a major role in the origins of the Oxus civilization inhabitants of the north Bactrian oasis.

Adult↗
PubMed2005

The origin of dihydroorotate dehydrogenase genes of kinetoplastids, with special reference to their biological significance and adaptation to anaerobic, parasitic conditions.

Trypanosoma cruzi dihydroorotate dehydrogenase (DHOD), the fourth enzyme of the de novo pyrimidine biosynthetic pathway, is localized in the cytosol and utilizes fumarate as electron acceptor (fumarate reductase activity), while the enzyme from other various eukaryotes is mitochondrial membrane-linked. Here we report that DHOD-knockout T. cruzi did not express the enzyme protein and could not survive even in the presence of pyrimidine nucleosides, substrates for the potentially active salvage pathway, suggesting a vital role of fumarate reductase activity in the regulation of cellular redox balance. Cloning and phylogenetic analysis of euglenozoan DHOD genes showed that the euglenoid Euglena gracilis had a mitochondrial DHOD and that biflagellated bodonids, a sister group of trypanosomatids within kinetoplastids, harbor the cytosolic DHOD. Further, Bodo saliens, a bodonid, had an ACT/DHOD gene fusion encoding aspartate carbamoyltransferase (ACT), the second enzyme of the de novo pyrimidine pathway, and DHOD. This is the first report of this novel gene structure. These results are consistent with suggestions that an ancient common ancestor of Euglenozoa had a mitochondrial DHOD whose descendant exists in E. gracilis and that a common ancestor of kinetoplastids (bodonids and trypanosomatids) subsequently acquired a cytosolic DHOD by horizontal gene transfer. The cytosolic DHOD gene thus acquired may have contributed to adaptation to anaerobiosis in the kinetoplastid lineage and further contributed to the subsequent establishment of parasitism in a trypanosomatid ancestor. Different molecular strategies for anaerobic adaptation in pyrimidine biosynthesis, used by kinetoplastids and by euglenoids, are discussed. Evolutionary implications of the ACT/DHOD gene fusion are also discussed.

Adaptation, Physiological↗
PubMed2003

The biological and metabolic adaptations to 12 months training in elite rowers.

We studied the effects of a twelve months endurance-training program on exercise-induced change in blood contents in thirteen rowers. A standardized testing-session (18 km rowing at 80 % of VO2max) was performed 19 times during the training program. Capillary blood samples were taken at rest and immediately post-exercise to analyse a wide range of serum concentrations. During exercise, glucose and lactate concentrations stabilized after only five training weeks and did not evolve from that point. Transport and hepatic protein concentrations increased with exercise up to the 15th week (p = 0.03), and remained stable from that point (p = 0.02). Evolution of exercise-induced change in alpha 1 -acid glycoprotein concentration revealed protein metabolism adaptations to training. Change in alpha 1 -acid glycoprotein concentrations were exactly opposite to that of urea and alpha 1 -antitrypsin (p = 0.01 and 0.002, respectively). Immunoglobulin concentrations exhibited important increases up to the 6th training week (p < 0.05), and a global stabilization was observed from that point. However, analysis of IgG subclasses highlighted significant changes that could not be found with the study of total IgG concentrations. Evolution of the exercise-induced change in Apo-A 1 /Apo-B concentrations ratio was also more informative about lipid metabolism than the Apo-A 1 and Apo-B concentrations taken individually. Indeed, evolution of metabolic changes during exercise should be carefully monitored during training to avoid interpretative errors on the training status of athlete.

Adaptation, Physiological↗
PubMed2001

[Patient-adapted valve selection: biological vs. mechanical heart valve replacement in aortic valve diseases].

Since the first aortic valve replacement performed by Harken in 1960, the operation of aortic valve disease by replacing the native valve with a heart valve prosthesis has become one of the most frequently performed procedures in cardiac surgery. For valve replacement there are biological (xenografts and homografts) and mechanical heart valve prostheses available. When choosing the most suitable prosthesis the limited durability of a biological prosthesis and the risks of lifelong anticoagulation for a mechanical prosthesis have to be balanced. In this article the indication for operation of aortic valve stenosis and aortic regurgitation are discussed first. Based on the literature of the last 2 years the advantages and disadvantages of mechanical and biological heart valve prostheses (xenograft, homograft and ROSS procedure) are discussed. In addition rarely used techniques like aortic valve reconstruction are presented. Due to the fact that a biological prosthesis has a durability of 12-15 years and the risk of bleeding complications under anticoagulation grows with increasing age, the choice of a biological prosthesis can be recommended from the age of 65 years. Results of long-term studies at to whether this limit can be diminished by using a stentless biological prosthesis have to be awaited.

Aged↗