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PubMed1982

Neural networks and physical systems with emergent collective computational abilities.

Computational properties of use of biological organisms or to the construction of computers can emerge as collective properties of systems having a large number of simple equivalent components (or neurons). The physical meaning of content-addressable memory is described by an appropriate phase space flow of the state of a system. A model of such a system is given, based on aspects of neurobiology but readily adapted to integrated circuits. The collective properties of this model produce a content-addressable memory which correctly yields an entire memory from any subpart of sufficient size. The algorithm for the time evolution of the state of the system is based on asynchronous parallel processing. Additional emergent collective properties include some capacity for generalization, familiarity recognition, categorization, error correction, and time sequence retention. The collective properties are only weakly sensitive to details of the modeling or the failure of individual devices.

Animals↗

PubMed1967

Biogenesis of chloroplast membranes. II. Plastid differentiation during greening of a dark-grown algal mutant (Chlamydomonas reinhardi).

Dark-grown cells of the y-1 mutant of Chlamydomonas reinhardi contain a partially differentiated plastid lacking the photosynthetic lamellar system. When exposed to the light, a rapid synthesis of photosynthetic membranes occurs accompanied by synthesis of chlorophyll, lipids, and protein and extensive degradation of the starch reserve. The process is continuously dependent on illumination and is completed within 6-8 hr in the absence of cell division. Photosynthetic activity (O(2) evolution, Hill reaction, NADP photo-reduction, and cytochrome f photooxidation) parallels the synthesis of pigment and membrane formation. During the greening process, only slight changes occur in the levels of soluble enzymes associated with the photosynthetic process (RuDP-carboxylase, NADP-linked G-3-P dehydrogenase, alkaline FDPase (pH 8)) as compared with the dark control. Also cytochrome f concentration remains almost constant during the greening process. The kinetics of the synthesis of chlorophyll, formation of photosynthetic membranes, and the restoration of photosynthetic activity suggest that the membranes are assembled from their constituents in a single-step process.

Autoradiography↗

PubMed2004

Identification of clinically relevant viridans group streptococci by sequence analysis of the 16S-23S ribosomal DNA spacer region.

The feasibility of sequence analysis of the 16S-23S ribosomal DNA (rDNA) intergenic spacer (ITS) for the identification of clinically relevant viridans group streptococci (VS) was evaluated. The ITS regions of 29 reference strains (11 species) of VS were amplified by PCR and sequenced. These 11 species were Streptococcus anginosus, S. constellatus, S. gordonii, S. intermedius, S. mitis, S. mutans, S. oralis, S. parasanguinis, S. salivarius, S. sanguinis, and S. uberis. The ITS lengths (246 to 391 bp) and sequences were highly conserved among strains within a species. The intraspecies similarity scores for the ITS sequences ranged from 0.98 to 1.0, except for the score for S. gordonii strains. The interspecies similarity scores for the ITS sequences varied from 0.31 to 0.93. Phylogenetic analysis of the ITS regions revealed that evolution of the regions of some species of VS is not parallel to that of the 16S rRNA genes. One hundred six clinical isolates of VS were identified by the Rapid ID 32 STREP system (bioMérieux Vitek, Marcy l'Etoile, France) and by ITS sequencing, and the level of disagreement between the two methods was 18% (19 isolates). Most isolates producing discrepant results could be unambiguously assigned to a specific species by their ITS sequences. The accuracy of using ITS sequencing for identification of VS was verified by 16S rDNA sequencing for all strains except strains of S. oralis and S. mitis, which were difficult to differentiate by their 16S rDNA sequences. In conclusion, identification of species of VS by ITS sequencing is reliable and could be used as an alternative accurate method for identification of VS.

DNA, Ribosomal Spacer↗

PubMed1979

A ten-year retrospective study of sepsis in severely burned patients treated with or without silver sulfadiazinate.

Three groups of extensive burn patients of the surgical intensive care unit (ICU) have been compared: Group I: twenty patients, who were treated locally without silver sulfadiazinate (1968-1970); Group II: the twenty first patients topically treated with silver sulfadiazinate (1970-1972); Group III: twenty similarly treated patients, with silver sulfadiazinate, six years later (1976-1977). The groups are statistically comparable. All bacteriological samples were computerized; the chi-square method was used for statistical analysis of the data. The main conclusions are: (A) Silver sulfadiazinate treatment reduced Pseudomonas aeruginosa and Proteus sepsis. No change in Coliform bacilli sepsis was observed. After six years, a rise in Klebsiella sepsis and Candida sepsis was noted. (B) A quantitative estimate of infections in each group was made by measuring the percentage of positive samples, taking into account the five above-mentioned strains. In the beginning, silver sulfadiazinate reduced quantitative sepsis, but this benefit decreased after six years; the same evolution was demonstrated for positive blood bacteriology; severe septicaemia showed a parallel pattern.

Burns↗

PubMed1997

Rhabdomyolysis due to hyperosmolarity leading to acute renal failure.

Authors present the case of a 37-year-old man admitted to the emergency room of Universidade Federal de São Paulo-Escola Paulista de Medicina, with hyperosmolar coma, following progressive muscle discomfort and loss of renal function, with further need of dialysis therapy. Initial laboratory evaluation showed marked hyperglycemia, hypernatremia, hyperosmolarity, and high levels of creatinine. In the evolution he presented an elevation of creatino-phosphokinase levels in parallel with increasing levels of urea and creatinine. Urinalyses showed progressive increase in proteinuria and hematuria. A muscle biopsy was performed and confirmed the presence of muscular necrosis. The purpose of this paper is to emphasize hyperosmolarity as a newly described cause of rhabdomyolysis. The authors point out its multifactorial physiopathology and also stress the relatively common occurrence of acute renal failure (ARF) following an episode of rhabdomyolysis, and the poor prognosis that this complication represents.

Acute Kidney Injury↗

PubMed2003

Laboratory diagnosis of immune heparin-induced thrombocytopenia.

Immune heparin-induced thrombocytopenia (HIT) is a distinct immunohematologic syndrome in which laboratory detection of the pathogenic HIT antibodies is diagnostically useful. Assays can be broadly classified as platelet activation assays (which detect HIT antibodies based on their characteristic platelet-activating properties) and antigen assays (which measure antibodies reactive against platelet factor 4 complexed with heparin or other polyanions). Available tests vary considerably in their sensitivity-specificity profiles for detecting the antibodies and in their predictive values. The high sensitivity of certain assays means that HIT can be readily ruled out (high negative predictive value). However, because heparin-treated patients often generate nonpathogenic antibodies, a positive test does not necessarily indicate clinical HIT. Laboratory methods for detecting HIT antibodies have undergone an evolution similar to that of red blood cell serology and which parallels the Goldilocks tale, that is, progression from too insensitive (too hard) to too sensitive (too soft) to "just right." However, optimal diagnostic information requires that laboratory test results be interpreted in the appropriate clinical context.

Clinical Laboratory Techniques↗

PubMed1975

[Mixed tumors and cylindromas].

The lacrimals glands may be the focus of the pleomorphic tumours with the same property as the major and minor salivary glands. Their localisation causes different clinical and therapeutic consequences. The cylindromes or Adenoid Cystic Carcinoma are to be put on a parallel with the pleomorphic tumours, though the issue of the clinical evolution is very different for each of them.

Adenoma, Pleomorphic↗

PubMedDate not supplied

The evolution of surgery at the New York Hospital.

Surgery evolved from colonial times through many innovations and developments. During this time it was transformed from a dangerous practice to a delicate and scientific art. Many of these early developments continue to be a part of modern surgical therapy. Although European discoveries have had a profound effect on this evolution, American advances solidified the link between the laboratory and the operating room. The New York Hospital-Cornell Medical Center, like other medical centers around the country, made important contributions to this evolution. Because the hospital has spanned American history, it also has paralleled surgical development in the United States.

Education, Medical↗

PubMed1991

[Doppler echocardiographic evaluation of the efficacy of fibrinolytic treatment of pulmonary embolism].

The efficacy of the fibrinolytic therapy in pulmonary embolism was studied by Doppler echocardiography: the evolution of the cardiac and angiographic changes could be studied in parallel. Thirty patients with severe pulmonary embolism and vascular obstruction greater than 40% (67.2 +/- 9.9%) were examined prospectively by Doppler echocardiography before and after thrombolysis. The following parameters were studied: systolic pulmonary artery pressure calculated from the jet of tricuspid regurgitation and left and right ventricular diameters for the calculation of the ratio of the ventricular dimensions. All patients underwent Doppler echocardiography and pulmonary angiography immediately after thrombolysis. The average improvement of the percentage vascular obstruction was 37%. The hemodynamic and echocardiographic changes were globally favourable. The pulmonary artery systolic pressure fell from 51 +/- 10 to 33 +/- 6.7 to 25.3 +/- 6.3 mm and the ratio of ventricular dimension from 0.87 +/- 0.3 to 0.60 +/- 0.16 (p less than 0.001). Only 4 patients had pulmonary artery systolic pressures over 40 mmHg after therapy compared with 26 before therapy. However, the hemodynamic and angiographic correlations were poor (r = 0.37; p less than 0.001). In the 6 patients in whom treatment was ineffective according to angiographic criteria (less than 20% improvement of vascular obstruction), the echocardiographic changes were small or absent, the improvement in the ratio of ventricular dimensions being less than 20%. However, a satisfactory correlation was observed between the percentage improvement of the ratio of ventricular dimensions and that of vascular obstruction (r = 0.59; p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1986

[Aortic insufficiency in certain so-called systemic diseases].

The authors present a retrospective study of all the patient followed up for systemic disease in the rheumatology Department of Bichat hospital between 1975 and 1984 in whom aortic regurgitation developed. Only rare or previously undescribed associations were retained: two MacDuffie syndromes, one adult form of Still's disease, one Takayashu's disease, one association of rheumatoid arthritis and Takayashu's disease, one rheumatoid arthritis, one Cogan's syndrome and two cases of disseminated lupus erythematosis. The authors use these cases and a review of the literature to discuss the possible physiopathological mechanisms of the aortic regurgitation. This study confirms the value of regular clinical cardiovascular examination with echocardiography in cases with progressive symptoms. The evolution of the vascular disease seems to be more or less parallel to that of the systemic disease and in a significant number of cases it becomes sufficiently severe to become the main clinical problem. In our series, there was one sudden death, one death due to cardiogenic pulmonary oedema and three patients required aortic valve replacement.

Adult↗

PubMed1995

[The borders of hysteria].

Medical writing dealing with the nosology of hysteria has evolved through successive national and international classifications, while in parallel the expression of hysteria has changed with time, with cultural evolution and with increased medical knowledge. Hysteria, by definition, is distinguished both by psychic or physical symptoms reported or voluntarily induced by patients (simulation or pathomimic behaviour) and by somatic disorders having an underlying, associated organic pathology, favoured by an emotional context or a conflictual situation (psychosomatic disorders). The divergence, but above all the analogies between hysterical symptoms and such limits are underlined, showing the frequency of succession with time, associations and transitional forms ("somatisation disorder" of the DSM III, psychogenic pain, and psychosomatic disorders termed "psychofunctional").

Humans↗

PubMed2004

Generality of the structurally constrained protein evolution model: assessment on representatives of the four main fold classes.

The Structurally Constrained Protein Evolution (SCPE) model simulates protein evolution by introducing random mutations into the evolving sequences and selecting them against too much structural perturbation. Given a single protein structure, the SCPE model can be used to obtain a whole set of site-dependent amino acid substitution matrices. The set of SCPE substitution matrices for a given protein family can be seen as an independent-sites model of evolution for that family. Thus, these matrices can be compared with other substitution-matrix-based models of evolution. So far, SCPE has been tested only on left-handed parallel beta helix (LbetaH) proteins. Here, we address the question of generality by assessing the SCPE model on representatives of the four main classes of folds: alpha, beta, alpha+beta, and alpha/beta. We compare with other models using the likelihood ratio test with parametric bootstrapping. We show that SCPE performs better than the popular JTT model for all cases considered. Furthermore, by considering the relative contributions of mutation and selection, we found that the key to the success of the SCPE model is the selection step.

Algorithms↗

PubMed2002

Phylogeny, concerted convergence, and phylogenetic niche conservatism in the core Liliales: insights from rbcL and ndhF sequence data.

Calochortus and the family Liliaceae s.s. have often been considered each other's closest relatives, based partly on their shared possession of bulbs, visually showy flowers, winged wind-dispersed seeds, and narrow parallel-veined leaves. We present a well-supported molecular phylogeny for these groups and their close relatives in the core Liliales, based on sequence variation in the chloroplast-encoded rbcL and ndhF genes. This analysis identifies Liliaceae s.s. as monophyletic. including one clade (((Lilium, Fritillaris, Nomocharis), Cardiocrinum), Notholirion) that appears to have diversified in the Himalayas roughly 12 million years ago and another ((Erythronium, Tulipa), (Gagea, Lloydia)) that arose in East Asia at about the same time. Medeola and Clintonia are sister to Liliaceae s.s. and bear rhizomes, inconspicuous flowers, fleshy animal-dispersed fruits, and broad reticulate-veined leaves. Calochortus is sister to Tricyrtis; both Tricyrtis and the neighboring clade of Prosartes-Streptopus-Scoliopus share several of the traits seen in Medeola-Clintonia. The core Liliales thus provide compelling examples of both concerted convergence and phylogenetic niche conservatism. Invasion of open, seasonal habitats was accompanied by the independent evolution of bulbs, showy flowers, wind-dispersed seeds, and narrow parallel-veined leaves in Calochortus and Liliaceae s.s. Conversely, persistence in shady habitats was accompanied by the retention of rhizomes, inconspicuous flowers, animal-dispersed seeds, and broad reticulate-veined leaves in their sister groups. We advance arguments for the context-specific adaptive value of each of these traits, as well as evidence of parallel trends in other groups. Concerted convergence--convergence in several different traits, favored by the same shared set of ecological conditions, in two or more lineages--is an important evolutionary process that can mislead evolutionary analyses based solely on phenotypic variation.

Conserved Sequence↗

PubMedDate not supplied

Ontogeny, phylogeny and the origin of biological information.

Accepting the evidence that evolution is largely finished and that sexual reproduction is incapable of supporting macroevolution, indicates that macroevolutionary changes were produced presexually through the cytological events associated with the first meiotic division. This reproductive mode is ideally suited to the production of new structural rearrangements of preexisting genetic information in instantaneous homozygous form. These new arrangements (position effects) produce new and discrete species. Thus, speciation results not from new genetic information, but rather from information already present (preformed). The several parallels that exist between epigenesis and preformation in both ontogeny (development) and phylogeny (evolution) are discussed. I propose that both of these phenomena have proceeded through the selective activation (derepression) of an enormous potential supply of information already present at the onset of each of these biological phenomena. Acceptance of these possibilities can serve to liberate us in our quest for the ultimate truth concerning these two closely related phenomena.

Animals↗

PubMed2005

Pediatric meningosarcoma: clinical evolution and genetic instability.

This report presents a female diagnosed with a frontoparietal interhemispheric meningosarcoma who, parallel to the clinical worsening, revealed an increase in the genetic instability (in bleomycin cultures) and the complexity of the karyotypes, with the acquisition of a clonal deletion of 17p13 (the locus for the TP53 tumor suppressor gene). The genetic findings of this patient suggest that the increased genetic instability could contribute to tumor progression as well as to treatment resistance, possibly in the background of the clonal deletion of TP53.

Child↗

PubMed2005

Allometric scaling of flight energetics in orchid bees: evolution of flux capacities and flux rates.

The evolution of metabolic pathways involved in energy production was studied in the flight muscles of 28 species of orchid bees. Previous work revealed that wingbeat frequencies and mass-specific metabolic rates decline in parallel by threefold as body mass increases interspecifically over a 20-fold range. We investigated the correlated evolution of metabolic rates during hovering flight and the flux capacities, i.e. V(max) values, of flight muscle enzymes involved in substrate catabolism, the Krebs cycle and the electron transport chain. V(max) at the hexokinase (HK) step scales allometrically with an exponent almost identical to those obtained for wingbeat frequency and mass-specific metabolic rate. Analysis of this relationship using phylogenetically independent contrasts supports the hypothesis of correlated evolution between HK activity and mass-specific metabolic rate. Although other enzymes scale allometrically with respect to body mass, e.g. trehalase, glycogen phosphorylase and citrate synthase, no other enzyme activities were correlated with metabolic rate after controlling for phylogenetic relatedness. Pathway flux rates were used with enzyme V(max) values to estimate fractional velocities (fraction of V(max) at which enzymes operate) for various reactions to gain insights into enzyme function and how this varies with body mass. Fractional velocity is highly conserved across species at the HK step, but varied at all other steps examined. These results are discussed in the context of the regulation and evolution of pathways of energy metabolism.

Animals↗

PubMed2003

Marked intragenomic heterogeneity and geographical differentiation of nrDNA ITS in Larix potaninii (Pinaceae).

Nuclear ribosomal DNA (nrDNA) of gymnosperms, especially Pinaceae, is characterized by slow concerted evolution and exhibits substantial ITS-region length variation (975-3663 bp), in sharp contrast to the narrow range (565-700 bp) in angiosperms. Here we examined intra- and intergenomic heterogeneity of the nrDNA internal transcribed spacer (ITS) region in four varieties of Larix potaninii, a species from the mountainous areas of western China. Two clones with more than a 100-bp deletion in ITS1 were detected in L. potaninii var. chinensis and L. potaninii var. australis, respectively. The deletion resulted in the loss of most part, including the motif sequence, of subrepeat 1 (SR1). Sequence divergence and phylogenetic analyses showed that some clones would be pseudogenes given their low GC content, high substitution rates, unique positions in the phylogenetic trees, or significant length variation. These clones might represent orphons or paralogues at minor loci resulting from large-scale gene or chromosome reorganization. Some recombinants characterized by chimeric structure and discordant phylogenetic positions in partitioned sequence analyses indicate that unequal crossing-over plays an important role in the process of nrDNA concerted evolution. In addition, some varieties of L. potaninii might have experienced an nrDNA founder effect parallel to their geographical isolation.

Base Composition↗

PubMed1998

Biogeography and floral evolution of baobabs (Adansonia, Bombacaceae) as inferred from multiple data sets.

The phylogeny of baobab trees was analyzed using four data sets: chloroplast DNA restriction sites, sequences of the chloroplast rpl16 intron, sequences of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA, and morphology. We sampled each of the eight species of Adansonia plus three outgroup taxa from tribe Adansonieae. These data were analyzed singly and in combination using parsimony. ITS and morphology provided the greatest resolution and were largely concordant. The two chloroplast data sets showed concordance with one another but showed significant conflict with ITS and morphology. A possible explanation for the conflict is genealogical discordance within the Malagasy Longitubae, perhaps due to introgression events. A maximum-likelihood analysis of branching times shows that the dispersal between Africa and Australia occurred well after the fragmentation of Gondwana and therefore involved overwater dispersal. The phylogeny does not permit unambiguous reconstruction of floral evolution but suggests the plausible hypothesis that hawkmoth pollination was ancestral in Adansonia and that there were two parallel switches to pollination by mammals in the genus.

Animals↗