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PubMed1996

Chemotaxis of the unicellular green alga Dunaliella salina and the ciliated Tetrahymena pyriformis--effects of glycine, lysine, and alanine, and their oligopeptides.

Chemotactic properties of amino acids (L-alanine, glycine and L-lysine) and their oligopeptides (10(-6) M) and binding sites to these ligands were investigated in two unicellular models, the heterotrophic Tetrahymena pyriformis and the auxotrophic Dunaliella salina. Chemotaxis of Dunaliella induced by simple amino acids and their derivatives demonstrated that binding sites (receptors) for food molecules are not only present in the membrane but are also able to induce their basic physiological response. In Tetrahymena, substances with special molecular structure and properties (polar, hydrophilic character of the signal peptide chain)-5-L-Lys, 5-Gly- were required for chemoattraction, other peptides tested, lacking the required structure, were repellent. Divergences in chemotaxis and binding assays of both species suggest that trends of functional and binding parameters do not run parallel at this level of evolution.

Alanine↗

PubMed1984

Study of the evolution of acute phase reactants and of thromboxane and prostacyclin during calcium pyrophosphate-induced pleurisy in the rat.

By using a clearly defined model of acute inflammation in rats, CaPP-induced pleurisy, we compared the evolution of four APR levels (Hp, HpX, alpha 2M, SAP) at a local and peripheral site. At the same time we studied thromboxane and prostacyclin concentrations in pleural exudate. The levels of APR have shown a progressive increase up to 24 h. For alpha 2M, Hp, HpX the increase in serum concentration was more rapid than in exudate, whereas the evolution of SAP level was parallel in the intra and extra-vascular compartments. On the other hand the levels of albumin and transferrin which are not APR remained constant in serum and also in exudate from 6 h to 24 h. Thromboxane and prostacyclin levels reached a peak during the first two hours of the inflammatory reaction followed by a rapid decreased. These prostanoids may be considered as early and transient mediators of acute inflammation, whereas the acute phase proteins studied have a more prolonged role in the inflammatory reaction.

Acute-Phase Proteins↗

PubMed1998

Bazex syndrome (acrokeratosis paraneoplastica).

Acrokeratosis paraneoplastica (Bazex syndrome) is a rare but distinctive dermatosis associated with carcinomas of the upper aerodigestive tract with possible cervical lymph node metastases. The cutaneous lesions occurring in the syndrome are non-metastatic skin involvement that parallels (as cutaneous marker) the evolution of the malignancy. Since only a few case reports have been published in the otolaryngologic literature, we present our experience and review some of the findings previously reported.

Acrodermatitis↗

PubMed1983

Characterization of plasmids in aminocyclitol-resistant Staphylococcus aureus: electron microscopic and restriction endonuclease analysis.

Plasmid species isolated from aminocyclitol-resistant Staphylococcus aureus have been analyzed by restriction endonuclease digestion and electron microscopy. These plasmids can be divided into two interrelated groups; intergroup variability is due to the gain or loss of defined DNA sequences. Plasmids pSJ1 and pSJ24 are related to staphylococcal penicillinase plasmid pI524 which was first described over 20 years ago. Both pSJ1 and pSJ24 differ from pI524 by the acquisition of 8 and 4 kbp, respectively, and encode additional resistance to the antibiotics erythromycin and kanamycin. The gain of these resistance determinants suggests that the evolution of staphylococcal resistance plasmids parallels that observed for plasmids of gram-negative bacteria and has serious implications for the spread of antibiotic resistance among the staphylococci.

Aminoglycosides↗

PubMed1989

Serum levels of CA-50, CA-19.9, CA-125, neuron specific enolase and carcinoembryonic antigen in lung cancer and benign diseases of the lung.

The serum levels of five markers (CA-50, CA-19.9, CA-125, Enolase (NSE) carcinoembryonic antigen (CEA) were studied in 96 lung cancer patients and in 60 patients with benign diseases of the lung: sensitivity was 0.44, 0.41, 0.54, 0.23 and 0.38 respectively; specificity was 0.67, 0.87, 0.47, 0.93 and 0.97 respectively. Serum levels of CA-125 over 20 U/ml were found in 74% of patients with acute pneumonia. A good parallel existed between the clinical evolution of lung cancer and the variations in the serum level of CA-50, CA-19.9 and NSE. Although the pretreatment result was elevated, successive assays of the marker allowed the clinical evolution to be followed. Conflicting results were found with CA-125 and to a lesser extent with CEA. A close correlation existed between the serum levels CA-50 and CA-19.9 in the 2 groups of patients. In the absence of a specific marker for lung cancer, complementary information can be provided by means of a simultaneous determination of CEA, NSE, CA-19.9--or CA-50--and CA-125.

Adolescent↗

PubMed2005

Preparative expression of secreted proteins in bacteria: status report and future prospects.

The expression of heterologous secreted proteins in Escherichia coli is widely employed for laboratory and preparative purposes. Thanks to advances in expression technologies over the past 25 years, many mammalian proteins can now be produced routinely in secreted form with yields in the gram/litre scale. Nonetheless, ensuring efficient secretion across the inner membrane, and preventing proteolytic degradation, incorrect disulfide-bond formation and aggregation into periplasmic inclusion bodies, frequently presents significant challenges. Recent advances in the understanding of the periplasmic folding quality control system are leading to new strategies to facilitate the expression of heterologous secreted proteins. In parallel, protein design and directed evolution approaches are beginning to be exploited for engineering of the cellular protein folding machinery to achieve further improvements in protein expression.

Adenosine Triphosphatases↗

PubMed1996

Mammalian homologues of yeast vacuolar protein sorting (vps) genes implicated in Golgi-to-lysosome trafficking.

Sec1p, Vps33p, Vps45p and Sly1p constitute a family of proteins implicated in vesicle trafficking at distinct stages of the yeast secretory pathway. Several mammalian homologues of Sec1p have been described, including n-sec1 which has been implicated in the regulation of synaptic vesicle docking at the nerve terminal. We have characterized cDNA clones encoding three additional mammalian homologues belonging to this family: r-vps33a and r-vps33b from rat, which are 30 and 26% identical to yeast Vps33p, respectively, and h-vps45 from human which is 38% identical to yeast Vps45p at the amino acid (aa) level. Phylogenetic analysis of 16 Sec1p-related proteins from several species is consistent with the hypothesis that the evolution of this gene family parallels the specialization of vesicle trafficking to distinct intracellular compartments. By Northern analysis, each of these genes is expressed in all tissues examined (brain, spleen, lung, liver, skeletal muscle, kidney, testis). While n-sec1 binds syntaxin 1a, 2, and 3, r-vps33a, r-vps33b and h-vps45 do not bind any of the known syntaxins. We propose that the three proteins bind as yet unidentified syntaxin homologues involved in vesicle trafficking between the Golgi apparatus, prelysosomal compartment(s), and the lysosome.

Adult↗

PubMed2003

Assemblage of signaling DNA enzymes with intriguing metal-ion specificities and pH dependences.

We report a group of new DNA enzymes that possess a synchronized RNA-cleavage/fluorescence-signaling ability and exhibit wide-ranging metal-ion and pH dependences. These DNA catalysts were derived from a random-sequence DNA pool in a two-stage process: (1) establishment of a catalytic DNA population through repetitive rounds of in vitro selection at pH 4.0, and (2) sequence-diversification and catalytic-activity optimization through five parallel paths of in vitro evolution conducted at pH 3.0, 4.0, 5.0, 6.0, and 7.0, respectively. The deoxyribozymes were evolved to cleave the phosphodiester bond of a single ribonucleotide embedded in DNA and flanked immediately by two deoxyribonucleotides modified with a fluorophore and a quencher, respectively--a setting that synchronizes catalysis with fluorescence signaling. The most dominant catalyst from each pool was examined for metal-ion specificity, catalytic efficiency, pH dependence, and fluorescence-signaling capability. Individual catalysts have different metal-ion requirements and can generate as much as a 12-fold fluorescence enhancement upon RNA cleavage. Most of the DNA enzymes have a pH optimum coinciding with the selection pH and exhibit a rate constant approximating 1 min(-)(1) under optimal reaction conditions. The demonstration of DNA enzymes that are functional under extremely high acidity (such as pH 3 and 4) indicates that DNA has the ability to perform efficient catalysis even under harsh reaction conditions. The isolation of many new signaling DNA enzymes with broad pH optima and metal-ion specificities should facilitate the development of diverse deoxyribozyme-based biosensors.

Base Sequence↗

PubMed2001

A primitive sarcopterygian fish with an eyestalk.

The discovery of two Early Devonian osteichthyan (bony fish) fossils has challenged established ideas about the origin of osteichthyans and their divergence into actinopterygians (teleosts and their relatives) and sarcopterygians (tetrapods, coelacanths, lungfishes and related groups). Psarolepis from China and an unnamed braincase from Australia combine derived sarcopterygian and actinopterygian characters with primitive features previously restricted to non-osteichthyans, suggesting that early osteichthyan evolution may have involved substantial parallellism between sarcopterygians and actinopterygians. But interpretation of these fossils has been hampered by poor phylogenetic resolution. Here we describe a basal sarcopterygian fish, Achoania gen, et sp. nov., that fills the morphological gap between Psarolepis and higher sarcoptergyians. We also report the presence of eyestalk attachments in both Achoania and Psarolepis, showing that this supposedly non-osteichthyan feature occurs in basal sarcopterygians as well as the actinoptergyian-like Australian braincase.

Animals↗

PubMed2005

A paradigm of integrative care: healing with curing throughout life, "being with" and "doing to".

We are presenting an integrative paradigm of care. We will review the basis for its evolution from prior series and parallel models. In this paradigm, healing and palliation (when indicated) are introduced in parallel with curative measures as soon as any diagnosis, especially a critical one, is made. Frequently palliative measures address patient symptoms, such as pain, anxiety, delirium, or depression, and are geared towards comfort care at the end of life. Our view of healing care is that it actively addresses the cognitive, emotional and spiritual needs of the patient and family, and includes the elements of palliative care as a complement. Because a loss is often experienced in many conditions, even in the absence of death, bereavement is represented in our model as an ongoing, continual process throughout a disease process. While we will be drawing mainly from experiences with children, the proposed model is applicable to all ages. In order to implement this model most effectively, it will be important to shift from our mindset of "doing to" to one that includes "being with" our patients and their families. The uniqueness of this paradigm, in contrast to other models, is its comprehensiveness and universality. It is appropriate for patients of any age, at any stage of their disease or illness, regardless of the severity or duration of their condition.

Attitude of Health Personnel↗

PubMed2001

Ablation strategies reflect evolving concepts of atrial fibrillation mechanisms.

Atrial fibrillation (AF) is the most common arrhythmia seen in clinical practice and results in the largest number of arrhythmia related hospital admissions. Despite the enormity of its impact on patients and the health care system, current medical therapy for AF is inadequate. Therapeutic approaches have been guided by understanding of fibrillation mechanisms. AF results from multiple simultaneous reentrant wavefronts. This is a diffuse and dynamic substrate with no discrete anatomic target. The catheter mediated "Maze" procedure employs creation of linear lesions to divide the atria into segments too small to support reentrant activation. Using current catheter technology this is a challenging procedure with low success rates and high complication rates. The observation that rapid focal firing of atrial myocytes within the pulmonary veins initiates fibrillation in the majority of paroxysmal AF patients has led to an entirely new ablation strategy. The sites of firing that initiate AF are targeted for ablation. Thus the paradigm for AF ablation has changed dramatically from altering the substrate of ongoing fibrillation to elimination of the triggers that initiate fibrillation. Initial experience revealed that multiple sites in the pulmonary veins are capable of rapid firing. Unfortunately not all sites fire during an ablation procedure. Sites that are quiescent during an ablation procedure may result in AF recurrence despite acute success. Ablation strategy has thus changed yet again to electrical isolation of all pulmonary venous tissue from the left atrium. The evolution of ablation strategies has paralleled our understanding of AF mechanisms. Elucidation of the mechanisms responsible for venous firing may lead to more specific therapy for the prevention of AF in the future.

Atrial Fibrillation↗

PubMed1998

Amine binding and oxidation at the catalytic site for photosynthetic water oxidation.

Photosynthetic water oxidation occurs at the Mn-containing catalytic site of photosystem II (PSII). By the use of 14C-labeled amines and SDS-denaturing PAGE, covalent adducts derived from primary amines and the PSII subunits, CP47, D2/D1, and the Mn-stabilizing protein, can be observed. When PSII contains the 18- and 24-kDa extrinsic proteins, which restrict access to the active site, no 14C labeling is obtained. NaCl, but not Na2SO4, competes with 14C labeling in Mn-containing PSII preparations, and the concentration dependence of this competition parallels the activation of oxygen evolution. Formation of 14C-labeled adducts is observed in the presence or in the absence of a functional manganese cluster. However, no significant Cl- effect on 14C labeling is observed in the absence of the Mn cluster. Isolation and quantitation of the 14C-labeled aldehyde product, produced from [14C]benzylamine, gives yields of 1. 8 +/- 0.3 mol/mol PSII and 2.9 +/- 0.2 mol/mol in Mn-containing and Mn-depleted PSII, respectively. The corresponding specific activities are 0.40 +/- 0.07 micromol(micromol PSII-hr)-1 and 0.64 +/- 0.04 micromol(micromol PSII-hr)-1. Cl- suppresses the production of [14C]benzaldehyde in Mn-containing PSII, but does not suppress the production in Mn-depleted preparations. Control experiments show that these oxidation reactions do not involve the redox-active tyrosines, D and Z. Our results suggest the presence of one or more activated carbonyl groups in protein subunits that form the active site of PSII.

Amine Oxidase (Copper-Containing)↗

PubMed2002

Stable propagation of an ordered array of cracks during directional drying.

We study the appearance and evolution of an array of parallel cracks in a thin slab of material that is directionally dried, and show that the cracks penetrate the material uniformly if the drying front is sufficiently sharp. We also show that cracks have a tendency to become evenly spaced during the penetration. The typical distance between cracks is mainly governed by the typical distance of the pattern at the surface, and it is not modified during the penetration. Our results agree with recent experimental work, and can be extended to three dimensions to describe the properties of columnar polygonal patterns observed in some geological formations.

Journal Article↗

PubMed2002

Reconnection and the ideal evolution of magnetic fields.

A magnetic evolution is ideal if it is consistent with the field being embedded in a perfectly conducting fluid. Faraday's law implies the evolution is ideal when the parallel component of the electric field is the derivative of a scalar potential, a condition that generically holds in any local region of space. Reconnection requires the non-existence of such a potential. In systems with two periodic directions, non-existence focuses reconnection onto the surfaces in which the magnetic field lines close on themselves, the rational surfaces. This rational surface effect does not arise in astrophysics but does appear in periodic simulation codes. Effects that could give astrophysical reconnection are discussed.

Journal Article↗

PubMed1986

Nitrate and Ammonium Induced Photosynthetic Suppression in N-Limited Selenastrum minutum.

Nitrate-limited chemostat cultures of Selenastrum minutum Naeg. Collins (Chlorophyta) were used to determine the effects of nitrogen addition on photosynthesis, dark respiration, and dark carbon fixation. Addition of NO(3) (-) or NH(4) (+) induced a transient suppression of photosynthetic carbon fixation (70 and 40% respectively). Intracellular ribulose bisphosphate levels decreased during suppression and recovered in parallel with photosynthesis. Photosynthetic oxygen evolution was decreased by N-pulsing under saturating light (650 microeinsteins per square meter per second). Under subsaturating light intensities (<165 microeinsteins per square meter per second) NH(4) (+) addition resulted in O(2) consumption in the light which was alleviated by the presence of the tricarboxylic acid cycle inhibitor fluoroacetate. Addition of NO(3) (-) or NH(4) (+) resulted in a large stimulation of dark respiration (67 and 129%, respectively) and dark carbon fixation (360 and 2080%, respectively). The duration of N-induced perturbations was dependent on the concentration of added N. Inhibition of glutamine 2-oxoglutarate aminotransferase by azaserine alleviated all these effects. It is proposed that suppression of photosynthetic carbon fixation in response to N pulsing was the result of a competition for metabolites between the Calvin cycle and nitrogen assimilation. Carbon skeletons required for nitrogen assimilation would be derived from tricarboxylic acid cycle intermediates. To maintain tricarboxylic acid cycle activity triose phosphates would be exported from the chloroplast. This would decrease the rate of ribulose bisphosphate regeneration and consequently decrease net photosynthetic carbon accumulation. Stoichiometric calculations indicate that the Calvin cycle is one source of triose phosphates for N assimilation; however, during transient N resupply the major demand for triose phosphates must be met by starch or sucrose breakdown. The effects of N-pulsing on O(2) evolution, dark respiration, and dark C-fixation are shown to be consistent with this model.

Journal Article↗

PubMed2004

Testing geographical pathways of speciation in a recent island radiation.

Determining the mode, or geographical context, of speciation is a critical first step to understanding the evolutionary mechanisms that cause new species to arise. In this study, we estimated phylogenetic relationships in the cerasina species group of the Hawaiian cricket genus Laupala (Orthoptera: Gryllidae) to test competing phylogeographical hypotheses and thus infer the mode of speciation. A previous phylogenetic result based on nuclear sequence data suggested that populations of L. cerasina on the Big Island of Hawaii are the result of two independent colonizations from Maui, implying parallel speciation and convergent song evolution, and contradicting systematic hypotheses based on behavioural and morphological data. We used amplified fragment length polymorphisms to investigate further the relationships among species and populations in the cerasina species group. Results of these analyses provide a robust estimate of phylogenetic relationships and support the phylogeographical history indicated by behavioural and morphological data.

Animals↗

PubMed1994

Identification of three feline immunodeficiency virus (FIV) env gene subtypes and comparison of the FIV and human immunodeficiency virus type 1 evolutionary patterns.

Feline immunodeficiency virus (FIV) is a lentivirus associated with AIDS-like illnesses in cats. As such, FIV appears to be a feline analog of human immunodeficiency virus (HIV). A hallmark of HIV infection is the large degree of viral genetic diversity that can develop within an infected individual and the even greater and continually increasing level of diversity among virus isolates from different individuals. Our goal in this study was to determine patterns of FIV genetic diversity by focusing on a 684-nucleotide region encompassing variable regions V3, V4, and V5 of the FIV env gene in order to establish parallels and distinctions between FIV and HIV type 1 (HIV-1). Our data demonstrate that, like HIV-1, FIV can be separated into distinct envelope sequence subtypes (three are described here). Similar to that found for HIV-1, the pairwise sequence divergence within an FIV subtype ranged from 2.5 to 15.0%, whereas that between subtypes ranged from 17.8 to 26.2%. However, the high number of synonymous nucleotide changes among FIV V3 to V5 env sequences may also include a significant number of back mutations and suggests that the evolutionary distances among FIV subtypes are underestimated. Although only a few subtype B viruses were available for examination, the pattern of diversity between the FIV A and B subtypes was found to be significantly distinct; subtype B sequences had proportionally fewer mutations that changed amino acids, compared with silent changes, suggesting a more advanced state of adaptation to the host. No similar distinction was evident for HIV-1 subtypes. The diversity of FIV genomes within individual infected cats was found to be as high as 3.7% yet twofold lower than that within HIV-1-infected people over a comparable region of the env gene. Despite these differences, significant parallels between patterns of FIV evolution and HIV-1 evolution exist, indicating that a wide array of potentially divergent virus challenges need to be considered in FIV vaccine and pathogenesis studies.

Adaptation, Biological↗

PubMed1986

B-immunoblastic lymphoma arising in angioimmunoblastic lymphadenopathy.

We present a female patient with a B-immunoblastic lymphoma of the IgM-lambda type arising in angioimmunoblastic lymphadenopathy. An increased ratio of helper/inducer to suppressor/cytotoxic lymphocytes in the lymph node could have triggered the proliferation of B cells. Evolution of IgM cryoglobulinemia was paralleled by malignant transformation in the lymph node. A short-term in vitro chemosensitivity test could predict response to COP combination chemotherapy suggesting that in vitro chemosensitivity testing can be useful for the therapeutic management of angioimmunoblastic lymphadenopathy.

Antineoplastic Combined Chemotherapy Protocols↗