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Results for “Continuous Evolution”

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PubMed1993

Aphakia and artificial lens implants in the civil airman population.

The Federal Aviation Administration allows civilian airmen with aphakia to fly with waivered certificates. This study analyzes, in the civil airman population, the distribution of aphakia and intraocular lens (I.O.L.) implant by type (unilateral, bilateral), class of airman medical certificate, and gender, for a 4-year period (1982-85). Medical records were individually evaluated for all certified airmen who were carrying FAA-specific codes for the pathology categories during the study period. The prevalence of both aphakia and I.O.L. increased most for bilateral type and second-class certificate holders. During the study period, the prevalence of aphakia increased most for males and I.O.L. increased most for females. The incidence declined in both pathology categories during the later years of the study period. Implications for aeromedical certification of the increasing prevalence of aphakia and I.O.L. in the civil airman population are discussed. The modification of surgical procedures for cataract extraction and evolution of I.O.L. devices strongly suggests continued specialized aeromedical certification and clinical research review.

Aerospace Medicine↗

PubMed1993

[Thromboangiitis obliterans (Buerger's disease). Study of 41 cases].

BACKGROUND: The aim of this study was to know the prevalence, clinical and immunological characteristics and evolution of thromboangiitis obliterans. METHODS: Between 1982-1990 41 cases of thromboangiitis obliterans were diagnosed from among 373,899 patients registered (11/100,000) according to the clinical and arteriographic criteria. Of these 41 cases 40 were males with mean age 36 +/- 7 years (mean +/- SD) with only two cases being over 45 years of age. In 40 cases was followed for 44 +/- 29 months (mean +/- SD). RESULTS: All the patients had ischemia of the lower limbs, 34% of the upper limbs, 39% superficial thrombophlebitis, 53% Raynaud's phenomenon, 5% mesenteric ischemia, and 7% myocardial infarction. In 30 symptomatic patients anticardiolipin antibodies were determined and one patient was positive for IgG antibodies. In the 23 patients in whom HLA and anticollagen antibody studies were performed a significant increase was found in HLA-B35, HLA-B40 and type VI denaturalized anticollagen antibodies compared to controls. In general the evolution was progressive when the patients continued smoking and favorable when tobacco was given up except in 2 cases who stopped smoking and in whom the disease progressed and death occurred. The total number of patients who died during follow up was 3 (7%), 2 due to mesenteric ischemia and the third during i.v. infusion of PGE1. CONCLUSIONS: The results demonstrate that thromboangiitis obliterans is a rare disease in Spain. The involvement of visceral arteries is not very infrequent with worse prognosis when the mesenteric arteries are involved. There is a significant increase of determined HLA antigens and anticollagen antibodies in the patients with thromboangiitis obliterans.

Adult↗

PubMed1996

Structure and diversity of the TCR alpha-chain in a teleost fish.

T cell receptor beta-chain genes are well characterized in representatives of most vertebrate phyla, from sharks to mammals, but the molecular structure of complete TCR alpha-chains has not yet been established in cold-blooded vertebrates. We used a PCR approach to isolate cDNAs encoding putative teleost fish (Oncorhynchus mykiss, rainbow trout) TCR alpha-chains. Eight V alpha segments were identified, belonging to six different families, and the best amino acid sequence identity scores for these trout V alpha were all provided by mammalian V alpha or V delta sequences. Twenty-four (60.1 %) of the 39 analyzed V alpha segments belong to the V alpha 2 family, which has limited homology with mammalian V alpha/delta sequences and with the human V pre-B sequence. A total of 32 different J alpha segments were identified from 40 J alpha regions sequenced, suggesting that a large repertoire of J alpha segments is a characteristic of most vertebrates. The structural properties of the TCR alpha-chain complementarity-determining region 3 loop are well conserved between trout and mammals, suggesting that this region has been under continuous selective pressure in jawed vertebrate evolution. The trout C alpha segment has conserved N-terminal and transmembrane domains, but the C alpha intercysteine distance contains only 40 residues, significantly smaller as compared with mammals (49-56 residues). The conserved features of teleost fish TCR beta- and alpha-chains with their mammalian equivalents suggest that TCR-alpha beta receptors were still present in the common Devonian ancestors of modern teleost fish and mammals, about 450 million years ago.

Amino Acid Sequence↗

PubMedDate not supplied

[History and perspectives of electro-vectorcardiography].

A panoramic view of the development of electrovectorcardiography from its beginnings until the present is reported. The functional essence of this exploratory method is emphasized and the basic steps of its evolution are described: the bipolar or differential leads in the beginning, the distal unipolar leads and the initial vectorcardiography in the 30s, the proximal unipolar leads in the 40s, the His electrograms and intracavitary and thoracic mapping in the 60s and later, the continuous records on a magnetic band. The evolution from Einthoven's original electrocardiograph to the modern apparatus of direct inscription and cathode-ray oscillographs is also described. Finally, the contribution of the Mexican School to a rational approach to electrovectorcardiography and clarification of some aspects of myocardial electrophysiopathology is presented.

Electrocardiography↗

PubMed1999

Multiple MSP pseudogenes in a local repeat cluster on 1p36.2: An expanding genomic graveyard?

Chromosomal region 1p36.2 harbors an intriguing gene cluster of about 1 Mb. In addition to normal high-copy-number repeats, this cluster consists entirely of locally repeated sequences among which there are tRNA and small nuclear RNA (snRNA) genes. In 23 PACs and YACs from the 1p36.2 cluster, we identified eight different copies of a sequence with about 97% homology to the macrophage stimulating protein (MSP) gene located on chromosomal band 3p21. These MSP-like (MSPL) sequences on 1p36.2 are scattered over the repeat region. Nucleotide substitutions and single nucleotide deletions in exons of all identified MSPL genes on 1p36.2 mark them as pseudogenes. We constructed a phylogenetic tree of these sequences with their most likely order of origin in evolution. MSP from 3p21 could be identified as the ancestral sequence, a copy of which was captured into the cluster of tRNA and snRNA genes on 1p36.2 about 6 million years (MY) ago. MSP subsequently coamplified with the other sequences in the cluster. Analysis of the DNA of 18 individuals shows that the MSPL copy number is polymorphic, with a range of four to seven or more copies per haploid genome. Analysis of corresponding clusters in macaque chromosomes indicated an age for the tRNA/snRNA cluster of at least 30 MY. The MSPL sequence thus functions as a probe for the more recent primate evolution of this cluster and suggests a continuation of its unusual activity over the last 6 MY.

Animals↗

PubMed2000

On the evolution of handedness: a speculative analysis of Darwin's views and a review of early studies of handedness in "the nearest allies of man".

Scientists today who seek clues into the evolutionary origins of human handedness make extensive use of evidence from comparative studies, that is, studies that ask whether handedness occurs in other species, especially apes and monkeys, as the Darwinian principle of continuity would seem to imply, or whether it is uniquely human. Early investigations had the same goal and drew on much the same kind of evidence. In this article, I review studies of animal handedness in the period before 1859, when Darwin published On the Origin of Species, and afterward, through the 1st decade of the 20th century. Inasmuch as Darwin's published writings contain hardly any statements about handedness and none at all about its evolution and continuity across species, I also speculate about what Darwin himself might have said on the subject. To do this, I draw on his statements on related matters, such as the form and structure of the hand and the transition from a quadrupedal to bipedal stance, on other writers' reports and opinions about handedness with which he was familiar or likely to have been familiar, and finally, on clues from his own and only statement about animal handedness in an unpublished letter. I conclude by asking whether and how early investigators, lacking any statement by Darwin on the evolution of handedness, invoked his theory of evolution and his views on related matters in the interpretation of their findings.

Animals↗

PubMed1997

Continuous stability and evolutionary convergence.

A stochastic process of long-term evolution due to mutation and selection is defined over an asexually reproducing population, with selection according to a population game with a one-dimensional continuity of pure strategies. Limiting the analysis to mutations of small effect, it is shown that long-term dynamic stability in such a process is equivalent to continuous stability in the relevant population game. In the case of a one-dimensional strategy set (but not necessarily if the strategy set is multi-dimensional), this result is virtually independent of the distribution of mutations.

Animals↗

PubMed2006

Early continuous video-EEG in acute near-total intrauterine asphyxia.

The evolution of electroencephalographic changes after acute hypoxic-ischemic injury is poorly understood, as a clear time of insult is often absent and continuous electroencephalographic monitoring in the first 3 days after such injury has not been previously reported. Infants who suffer sudden profound asphyxia, often termed "acute near-total intrauterine asphyxia", have evidence of damage to the deep gray matter. In these infants it is possible to time the onset and duration of cerebral ischemia. This report describes early continuous video-electroencephalography from 3 hours after birth in an infant with the characteristic clinical and radiologic features of acute near-total intrauterine asphyxia.

Acute Disease↗

PubMed1992

Recent human evolution in East Asia and Australasia.

In both East Asia and Australasia arguments for evolutionary continuity between middle-late Pleistocene hominid populations and modern Homo sapiens are of long standing. In both regions, however, problems of chronological distribution, dating and preservation of hominid skeletal materials provide an effective barrier to extending regional sequences back to 'archaic' Homo sapiens or Homo erectus. The earliest securely dated modern Homo sapiens in East Asia are currently represented by Zhoukoudian Upper Cave at a minimum of 29 ka BP. In Australia skeletal remains of modern Homo sapiens have been dated to 26 ka BP, with archaeological materials at 38 to 50 ka BP. Late Pleistocene human skeletons from sites like Coobool Creek are morphologically and metrically outside the range of recent Australian Aboriginal populations. Similarly Liujiang and the Upper Cave crania can be distinguished from recent East Asian 'Mongoloids'. Evolutionary change within the Holocene needs to be taken into consideration when the evidence for regional evolutionary continuity is considered.

Animals↗

PubMed2005

Concerted and birth-and-death evolution of multigene families.

Until around 1990, most multigene families were thought to be subject to concerted evolution, in which all member genes of a family evolve as a unit in concert. However, phylogenetic analysis of MHC and other immune system genes showed a quite different evolutionary pattern, and a new model called birth-and-death evolution was proposed. In this model, new genes are created by gene duplication and some duplicate genes stay in the genome for a long time, whereas others are inactivated or deleted from the genome. Later investigations have shown that most non-rRNA genes including highly conserved histone or ubiquitin genes are subject to this type of evolution. However, the controversy over the two models is still continuing because the distinction between the two models becomes difficult when sequence differences are small. Unlike concerted evolution, the model of birth-and-death evolution can give some insights into the origins of new genetic systems or new phenotypic characters.

Animals↗

PubMed1999

C-reactive Protein Follow-up of Children With Acute Bacterial Meningitis.

Twenty-two children with bacterial meningitis were prospectively studied to follow C-reactive protein (CRP) in serum at admission, 2nd, 5th and 7th days of treatment, and in the cerebrospinal fluid (CSF) at admission, to investigate if there is any relationship of its levels with the clinical evolution. CRP was measured by latex agglutination and/or ELISA techniques with detection limits of 0.15mg/L and 0.9mg/L, respectively. Patients were classified according to clinical evolution in two groups: uneventful recovery (n=12) and complicated evolution (n=10). Clinical complications observed were: relapse of fever (8), persistent fever (4), arthritis (4), ventricle enlargement (2), subdural effusion (1), subdural empyema (1), ataxia (1), cervical hypotonia (1), deafness (1), endophthalmitis (1), acute otitis media (1), secondary skin infection (1) and treatment change due to poor clinical response (1). A significant fall in CRP serum levels was observed among the uneventful recovery group after admission. Distinctly, in the group with a complicated evolution CRP levels showed either secondary elevation or remained high continuously. Mean serum CRP levels were significantly lower in the uneventful recovery group than in the complicated evolution group on 5th day and on 7th day. CRP levels below 20mg/L on 5th and 7th days were associated with an uneventful recovery, and CRP levels higher than 20mg/L on those same days were associated with a complicated clinical evolution (p=0.01* and p=0.0015*, respectively). We conclude that serum CRP levels monitoring in children with bacterial meningitis represents a useful and objective information about the clinical evolution. This procedure is inexpensive and suitable for use in endemic areas lacking sophisticated laboratories.

Journal Article↗

PubMed1983

Acquisitive evolution of ribitol dehydrogenase in Klebsiella pneumoniae.

Selection in continuous culture of Klebsiella pneumoniae mutants that have gained the ability to utilize xylitol while also retaining regulatory control over ribitol utilization was achieved with a dual-substrate regime. Initial steady-state cultures of wild-type organisms were maintained with 0.005% (0.329 mM) ribitol. Mutants of various types proliferated when the composition of the limiting medium was changed to 0.005% ribitol plus 0.250% (16.43 mM) xylitol.

Culture Media↗

PubMedDate not supplied

Evolutions in hospital funding in Canada.

Although global funding continues to be the principal method used for hospital reimbursement in Canada, a number of provincial ministries of health have recently introduced supplementary funding approaches. These initiatives aim to replace the mentality of "what you spend is what you get" with a funding system that is based on what hospitals produce. This article compares such initiatives in British Columbia, Alberta, and Ontario. Aspects examined include the hospital "product", cost determination, incentives, the definition of equity, the figure of merit for funding, population-based funding, and quality.

Alberta↗

PubMed1988

l-Glutamate-Dependent Medium Alkalinization by Asparagus Mesophyll Cells : Cotransport or Metabolism?

Mechanically isolated Asparagus sprengeri Regel mesophyll cells cause alkalinization of the suspension medium on the addition of l-glutamate or its analog l-methionine-d,l-sulfoximine. Using a radiolabeled pH probe, it was found that both compounds caused internal acidification whereas l-aspartate did not. Fusicoccin stimulated H(+) efflux from the cells by 111% and the uptake of l-[U-(14)C]glutamate by 55%. Manometric experiments demonstrated that, unlike l-methionine-d,l-sulfoximine, l-glutamate stimulated CO(2) evolution from nonilluminated cells. Simultaneous measurements of medium alkalinization and (14)CO(2) evolution upon the addition of labeled l-glutamate showed that alkalinization was immediate and reached a maximum value after 45 minutes whereas (14)CO(2) evolution exhibited a lag before its appearance and continued in a linear manner for at least 100 minutes. Rates of alkalinization and uptake of l-[U-(14)C]glutamate were higher in the light while rates of (14)CO(2) evolution were higher in the dark. The major labeled product of glutamate decarboxylation, gamma-aminobutyric acid, was found in the cells and the suspension medium. Its addition to the cell suspension did not result in medium alkalinization and evidence indicates that it is lost from the cell to the medium. The data suggest that the origin of medium alkalinization is co-transport not metabolism, and that the loss of labeled CO(2) and gamma-aminobutyric acid from the cell result in an overestimation of the stoichiometry of the H(+)/l-glutamate uptake process.

Journal Article↗

PubMed2006

Comment on "Ongoing adaptive evolution of ASPM, a brain size determinant in Homo sapiens" and "Microcephalin, a gene regulating brain size, continues to evolve adaptively in humans".

Mekel-Bobrov et al. and Evans et al. (Reports, 9 Sept. 2005, p. 1720 and p. 1717, respectively) examined sequence data from modern humans within two gene regions associated with brain development, ASPM and microcephalin, and concluded that selection of these genes must be ongoing. We show that models of human history that include both population growth and spatial structure can generate the observed patterns without selection.

Adaptation, Biological↗

PubMed2003

Detecting instabilities of cardiac rhythm.

Diminished beat-to-beat variations in cardiac cycle lengths (CLs) are associated with poor prognosis after acute myocardial infarction and in patients with heart failure. Short-long-short sequences of cardiac cycles, or ultra-short rhythm instabilities, precede initiation of ventricular tachyarrhythmias in some patients. However, little is known about clinical or prognostic significance of abrupt short-term instabilities in CL (AICL) that occur minutes to hours before the event, in part because appropriate analytical methods are lacking. Although various techniques have been used to analyze CL changes, methods for analysis of AICL are limited. We compared performance of time domain, spectral, nonlinear, and pattern recognition techniques with respect to the detection and quantification of AICL. Because of high intra- and inter-subject variability of CL, pattern recognition techniques compared favorably to other studied methods. In continuous ambulatory ECG recordings, AICL occurred hours before spontaneous initiation of sustained atrial and ventricular arrhythmias in different patient populations. AICL were also found prior to the onset of spontaneous ventricular arrhythmias in a mouse model of congestive heart failure. To quantify AICL, we used the number of unstable orthogonal projection coefficients; this number gradually increased hours before the event. Removal of ectopic beats reduced but did not eliminate AICL. To illustrate potential physiological effects and temporal evolution of AICL, we used a simple, continuous, two-dimensional model of cardiac tissue governed by the Morris-Lecar equations. Computer simulations in this model showed that AICL may lead to gradual accumulation of spatial irregularities of the propagation wavefront giving rise to the initiation of reentry. Time-frequency analysis of the most significant eigenvectors of cardiac rhythm in subjects undergoing head-up tilt showed that AICL could indicate instabilities and unsuccessful adaptation of autonomic nervous system activity to physiological stimuli.

Animals↗

PubMed2005

[Hydro-colloidal dressings which release hydro-active silver].

The study presented is a multicentric, prospective, open and comparative study designed with the objective of evaluating the performance of an antibacterial hydrocolloid dressing with hydroactivated silver (Comfeel Plata), when used to activate the healing process in wounds with high bacterial load, clinical signs of infection or malodour. Additionally, once the wound bed was appropriately prepared, a comparison in terms of efficacy was made between, on the one hand, continued treatment with the antibacterial hydrocolloid dressing, and, on the other hand, continued treatment with other dressings specifically designed for the proliferative phase of healing. Included into this study were 43 patients with chronic ulcers who were divided into two parallel treatment groups: In one group, Comfeel Plata (Coloplast AIS) was used until complete wound healing or for a maximum of 10-12 weeks, and in the second group Comfeel Plata (Coloplast A/S) was used until a clean wound bed was obtained and until the wound showed signs of positive evolution, at which moment the treatment was continued until complete healing or for a maximum of 10-12 weeks with dressings without silver designed especially for the proliferative phase of healing [Alione, Comfeel or Biatain (Coloplast AIS)]. The results obtained from the various study parameters indicate that the use of Comfeel Plata in the treatment of infected or colonized wounds prepares the wound bed and facilitates more rapid healing, and that the use of Comfeel Plata effectively reduces pain and malodour. The results indicate that once a clean wound bed is obtained, the use of a dressing without silver specifically for the proliferative phase will facilitate healing.

Bandages, Hydrocolloid↗

PubMed1994

Stimulant-induced psychosis, the dopamine theory of schizophrenia, and the habenula.

While one of the original underpinnings of the dopamine theory of schizophrenia was the paranoid psychosis which often develops during the binges or speed runs of chronic amphetamine addicts (and, more recently, in cocaine addicts), neurochemical studies of such drug abusers or from animals given continuous stimulants in an effort to model stimulant psychoses have not played a major role in the further evolution of this theory. One clear persisting alteration produced by continuous amphetamine is a neurotoxicity to dopaminergic innervations in caudate. Yet continuous cocaine administration apparently does not induce a similar neurotoxicity and this makes this effect a poor candidate for an underpinning of stimulant psychoses. However, it has recently been found that both continuous amphetamine and cocaine induce a strong pattern of degeneration which is highly confined to the lateral habenula and its principal output pathway, fasciculus retroflexus. This finding has led to a reconsideration of the role of these structures in psychoses. The habenula, as the chief relay nucleus of the descending dorsal diencephalic system (consisting of stria medullaris, habenula and fasciculus retroflexus), is an important link between limbic and striatal forebrain and lower diencephalic and mesencephalic centers. Studies of glucose utilization have consistently shown the habenula to be highly sensitive to dopamine agonists and antagonists. Lesions of habenula produce a wide variety of behavioral alterations. The dorsal diencephalic system has major and predominantly inhibitory connections onto dopamine-containing cells and it mediates part of the negative feedback from dopamine receptors onto dopamine cell bodies. It represents one of the major inputs in brain to the raphe nuclei and has anatomical and functional connections to modulate important functions such as sensory gating through thalamus, pain gating through central gray and raphe and motor stereotypies and reward mechanisms through substantia nigra and the ventral tegmental area. It is argued that alterations in these pathways are ideal candidates for producing the behaviors which occur during psychosis and that future considerations of the circuitry underlying psychoses need to include this highly important but relatively neglected system.

Animals↗