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PubMed2004

Stochastic perturbations in vortex-tube dynamics.

A dual lattice vortex formulation of homogeneous turbulence is developed, within the Martin-Siggia-Rose field theoretical approach. It consists of a generalization of the usual dipole version of the Navier-Stokes equations, known to hold in the limit of vanishing external forcing. We investigate, as a straightforward application of our formalism, the dynamics of closed vortex tubes, randomly stirred at large length scales by Gaussian stochastic forces. We find that besides the usual self-induced propagation, the vortex tube evolution may be effectively modeled through the introduction of an additional white-noise correlated velocity field background. The resulting phenomenological picture is closely related to observations previously reported from a wavelet decomposition analysis of turbulent flow configurations.

Journal Article↗
PubMed1998

Micromorphology of the dorsal ocelli of the Oriental hornet.

The development of vision in animals throughout evolution has been reviewed by Sir Stewart Duke-Elder, whose survey of the sense of sight ranges from lowly Crustaceans to mammals and man. According to Duke-Elder each ocellus is formed by the "fusion of two or more ocelli, each with its own retina and pigment cup". This process of 'ocellation' probably occurred independently in a number of phyla. So far as Hymenoptera are concerned, at least in Bombus, only the median ocellus has retained any evidence of its 'dual' origin. In hornets, there are three ocelli which are organized on the dorsal part of the head and receive their innervation from the optical lobes that are located in the protocerebrum. Proceeding from the exterior to the interior, the ocelli are generally composed of a cornea, followed by corneogenic cell layers and then by a layer of sensory cells from which emerges the ocellar nerve. Thus, in wasps and hornets the ocelli consist of a group of visual cells beneath a common lens and they possibly accentuate the response to light stimuli that are perceived by the compound eyes. Recently, the ocelli have been ascribed roles in orientation and navigation. In honeybees the sensitivity of the ocelli to light at various wavelengths was compared with that of the compound eyes, and was found to be different, to wit: in the ocellus there were two peaks--one of UV light at a wavelength of 335-340 nm and the other of green light at 490 nm, whereas in compound eye the peaks were at 350 nm and 540 nm. From all the foregoing, it would seem that the role of the ocelli in insects in general and in hornets in particular is not yet sufficiently clear. The present study was undertaken to elucidate the structure of the ocelli in the Oriental hornet and possibly also their function.

Animals↗
PubMed2004

The putative malate/lactate dehydrogenase from Pseudomonas putida is an NADPH-dependent delta1-piperideine-2-carboxylate/delta1-pyrroline-2-carboxylate reductase involved in the catabolism of D-lysine and D-proline.

A Pseudomonas putida ATCC12633 gene, dpkA, encoding a putative protein annotated as malate/L-lactate dehydrogenase in various sequence data bases was disrupted by homologous recombination. The resultant dpkA(-) mutant was deprived of the ability to use D-lysine and also D-proline as a sole carbon source. The dpkA gene was cloned and overexpressed in Escherichia coli, and the gene product was characterized. The enzyme showed neither malate dehydrogenase nor lactate dehydrogenase activity but catalyzed the NADPH-dependent reduction of such cyclic imines as Delta(1)-piperideine-2-carboxylate and Delta(1)-pyrroline-2-carboxylate to form L-pipecolate and L-proline, respectively. NADH also served as a hydrogen donor for both substrates, although the reaction rates were less than 1% of those with NADPH. The reverse reactions were also catalyzed by the enzyme but at much lower rates. Thus, the enzyme has dual metabolic functions, and we named the enzyme Delta(1)-piperideine-2-carboxylate/Delta(1)-pyrroline-2-carboxylate reductase, the first member of a novel subclass in a large family of NAD(P)-dependent oxidoreductases.

Bacterial Proteins↗
PubMed2003

The cnm locus, a canine homologue of human autosomal forms of centronuclear myopathy, maps to chromosome 2.

Myotubular/centronuclear myopathies are a nosological group of hereditary disorders characterised by severe architectural and metabolic remodelling of skeletal muscle fibres. In most myofibres, nuclei are found at an abnormal central position within a halo devoid of myofibrillar proteins. The X-linked form (myotubular myopathy) is the most prevalent and severe form in human, leading to death during early postnatal life. Maturation of fibres is not completed and fibres resemble myotubes. Linkage analysis in human has helped to identify MTM1 as the morbid gene. MTM1 encodes myotubularin, a dual protein phosphatase. In families in which myotubular myopathy segregates, detected mutations in MTM1 abolish the specific phosphatase activity targeting the second messenger phosphatidylinositol 3-phosphate. Autosomal forms (centronuclear) have a later onset and are often compatible with life. At birth, fibres are normally constituted but progressively follow remodelling with a secondary centralisation of nuclei. Their prevalence is low; hence, no linkage data can be performed and no molecular aetiology is known. In the Labrador Retriever, a spontaneous disorder strikingly mimics the clinical evolution of the human centronuclear myopathy. We have established a canine pedigree and show that the disorder segregates as an autosomal recessive trait in that pedigree. We have further mapped the dog locus to a region on chromosome 2 that is orthologous to human chromosome 10p. To date, no human MTM1 gene member has been mapped to this genetic region. This report thus describes the first spontaneous mammalian model of centronuclear myopathy and defines a new locus for this group of diseases.

Animals↗
PubMed2006

Multiphoton microscopy for the investigation of dermal penetration of nanoparticle-borne drugs.

Multiphoton microscopy (MPM) of a dually fluorescence-labeled model system in excised human skin is employed for high-resolution three-dimensional (3D) visualization in order to study the release, accumulation, and penetration properties of drugs released from nanoscale carrier particles in dermal administration. Polymer particles were covalently labeled with fluorescein, whereas Texas Red as a drug-model was dissolved in the particles to be released to the formulation matrix. Single nanoparticles on skin could easily be localized and imaged with diffraction-limited resolution. The temporal evolution of the fluorescent drug-model concentration in various skin compartments over more than 5 hours was investigated by multiphoton spectral imaging of the same area of the specimen. The 3D penetration profile of the drug model in correlation with skin morphology and particle localization information is obtained by multiple laser line excitation experiments. MPM combined with spectral imaging was found to allow noninvasive long-term studies of particle-borne drug-model penetration into skin with subcellular resolution. By dual color labeling, a clear discrimination between particle-bound and released drug model was possible. The introduced technique was shown to be a powerful tool in revealing the dermal penetration properties and pathways of drugs and nanoscale drug vehicles on microscopic level.

Fluorescence↗
PubMed1984

The role of the intensive care unit in a district hospital.

The evolution of an intensive care facility in a District General Hospital is recorded. Optimum use of the Unit was achieved by accepting both critically ill and high dependency care patients. This has been of benefit to both the staff and patients and may be reflected in the falling mortality of the critically ill surgical patient. High dependency care patients now only stay 1.3 days and there has been no mortality. In view of the ageing population and the cost of such units, this dual role in the District General Hospital Intensive Care Unit appears justified.

Adult↗
PubMed1995

Prevention of postmenopausal bone loss by rectal calcitonin.

A group (150) of healthy women, who had been menopausal for less than 5 years and who had never received any form of treatment to prevent bone loss were entered into a randomized, controlled study comprising three arms. They were randomly allocated to the double-blind administration of five suppositories per week containing either 100 IU of salmon calcitonin or a placebo, or to a group receiving a suppository containing 200 IU of salmon calcitonin three times per week. All women received 500 mg/day of calcium supplementation. After 12 months, bone mineral density (BMD) of the spine, measured by dual energy X-ray absorptiometry, decreased significantly (P < 0.01) in the placebo group by 3.1% (SD: 3.6%) but did not change in the two calcitonin groups [+1.3% (3.5%) with 100 IU/day and +2.3% (4.0%) with 200 IU 3/week]. The differences in response between the placebo group and the two calcitonin groups were significant (P < 0.05), but the difference between the two regimens of calcitonin administration was not. No differences appeared among the three groups for the response at the level of the hip. Evolution of biochemical markers reflecting bone turnover did not differ significantly among groups. Nearly 40% of the women withdrew prematurely because of local (rectal or intestinal) intolerance to repetitive suppositories, with a nonsignificantly different frequency in the placebo or calcitonin groups. We conclude that rectal calcitonin might be an interesting preventive approach against trabecular postmenopausal bone loss but that long-term acceptability of suppositories should be evaluated in view of each patient's sensibility or cultural background.

Administration, Rectal↗
PubMed2006

[Anterior chamber migration of Supramid tube from short Krupin valves after more than 13 years of implantation. Two case reports].

INTRODUCTION: In 2004, the authors had to remove two short Krupin valves because the Supramid tube of these valves implanted 13 years previously had migrated into the anterior chamber. CASE REPORT: The first case was treated in April 2004, the second in November 2004. These valves had been implanted in January 1991 and August 1983 respectively; both because of insufficient, intense general and local medical treatments for vascular glaucoma: post-traumatic for one and neovascular glaucoma after central retinal vein occlusion for the other. RESULTS: In 2004 in each case, the authors performed the extraction, with Healon, of the Supramid tube that had migrated into the anterior chamber and the dissection of the previous scleral flap, which allowed them to uncover and extract the Silastic scleral tube whose split distal end continued to allow seepage of aqueous humour. The two lateral Supramid arms used to stitch the valve were also removed. The two valves were replaced with a Molteno glaucoma drainage implant. Follow-up was simple. DISCUSSION: Since February 1981, several Krupin valves, first short, then long, were placed in the Ophthalmic Ward of the Villeneuve St Georges Hospital in France. The authors discuss their structure and evolution. The design of these valves, at first made of two different materials (an intracameral Supramid tube followed by a intrascleral Silastic tube) evolved toward a draining tube made from the same material for its entire length, preventing the disconnection of the two tubes. A literature review retraces the history of the device and the modifications over time. CONCLUSION: These old Krupin valves have stabilized the IOP for several years in numerous glaucoma patients who did not respond to intense medical treatments. Their dual-material concept was redesigned in favor of a single tube that could no longer become a mobile intraocular foreign body.

Aged↗
PubMed2001

State-of-the-art chamber facility for studying atmospheric aerosol chemistry.

A state-of-the-art chamber facility is described for investigation of atmospheric aerosol chemistry. Dual 28 m3 FEP Teflon film chambers are used to simulate atmospheric conditions in which aerosol formation may occur. This facility provides the flexibility to investigate dark, single oxidant reactions as well as full photochemical simulations. This paper discusses the environmental control implemented as well as the gas-phase and aerosol-phase instrumentation used to monitor atmospheric aerosol formation and growth. Physical processes occurring in the chamber and procedures for estimating secondary organic aerosol formation during reaction are described. Aerosol formation and evolution protocols at varying relative humidity conditions are presented.

Aerosols↗
PubMed2003

Evolution and nomenclature of the zona pellucida gene family.

Three subfamilies of genes are acknowledged within the zona pellucida (ZP) gene family. At present, these subfamilies each have two names that are used interchangeably: ZPA or ZP2, ZPB or ZP1, and ZPC or ZP3. The ZPA genes encode the longest protein sequences and the ZPC genes the shortest. Recently, several sequences, which have no clear relationship to the three subfamilies, have been identified. These sequences include two paralogous ZP genes from Xenopus laevis and a single gene from the fish Oryzias latipes. We have conducted extensive phylogenetic analyses of the known ZP genes. As well as establishing the evolutionary relationships among these genes, the analyses make it clear that the dual nomenclature system is no longer feasible, because major paralogous groups are present in the ZPB (ZP1) family of genes of amniotes. We propose a unified system of nomenclature for the ZP gene family that removes the existing ambiguities.

Animals↗
PubMed1962

Parallel induction of D-arabitol and D-sorbitol dehydrogenases.

Scolnick, Edward M. (Harvard Medical School, Boston, Mass.) and Edmund C. C. Lin. Parallel induction of d-arabitol and d-sorbitol dehydrogenases. J. Bacteriol. 84:631-637. 1962.-Two inducible diphosphopyridine nucleotide-linked dehydrogenases are described in a bacterium isolated from the soil, Cellvibrio polyoltrophicus ATCC 14774. The first enzyme catalyzes the dehydrogenation of d-arabitol to d-xylulose and d-mannitol to d-fructose. The data suggest that in vivo this enzyme has the dual function of the utilization of both of these polyhydric alcohols. The second enzyme was found to act only on d-sorbitol, converting it to d-fructose. Evidence for its physiological function as a d-sorbitol dehydrogenase is also given. Both of these enzymes were found to be induced in parallel by any of the three polyhydric alcohols, d-arabitol, d-mannitol, and d-sorbitol. A common stereoconfiguration of the inducers for these enzymes is suggested. The parallel evolution of substrate specificity and inducer specificity is discussed with respect to the functional advantage that such a selective process might offer.

Alcohols↗
PubMed1998

Dual energy X-ray absorptiometry of the hand and wrist--a possible technique to assess skeletal maturation: methodology and data in normal youths.

Ninety five normal Caucasian subjects (51F, 44M) aged from 2 to 25 y were measured at the hand and wrist level with a small DXA system (pDEXA) in order to obtain the normal values of the bone mineral content (BMC), density (BMD) and projected area (A) of carpal (c) and metacarpal (m) bones. BMDc ranged from 0.065 +/- 0.007 g/cm2 to 0.365 +/- 0.035 g/cm2 in females and 0.425 +/- 0.040 g/cm2 in males. It presented a sharp change of increase rate at 15.5 and 17 y of age in girls and boys, respectively. Ac presented the same kind of evolution as BMDc, but had a larger value dispersion. The second metacarpal bone had the highest BMCm value in 85% of females and 90% of males. The sum of BMCmi or Ami values (i = 1-5) and the projected mean density of the 5 metacarpal bones was well correlated with BMCc, Ac and BMDc, respectively (r > 0.90). A volumetric mineral density, dmi, calculated for each of these bones, approximated to a cylinder, was correlated with age (r > 0.85).

Absorptiometry, Photon↗
PubMed1981

Dual effect of carbonic anhydrase inhibitors on H+ transport by the turtle bladder.

Previous studies in isolated turtle bladder have demonstrated that high concentrations of carbonic anhydrase (CA) inhibitors limit H+ transport (JH) by reducing the catalyzed rate of CO2 hydroxylation and also by inhibiting some other step in the acidification process. One possibility is that these inhibitors alter the energy substrate requirement for JH. Recent work has demonstrated that JH may be dependent in part on glucose oxidation via the pentose shunt (PS). The present study was undertaken to determine whether CA inhibitors exert a direct effect on PS metabolism by turtle bladder. Acetazolamide and benzolamide at concentrations of 5 X 10(-4) M significantly reduced the rate of 14CO2 evolution from [1-14C]- but not [6-14C]glucose after JH was abolished by an adverse electrochemical gradient for JH+. These changes are consistent with a reduction in PS metabolism. These same sulfonamides also reduced glucose-6-phosphate dehydrogenase (G-6-PD) activity in mucosal cell homogenates. Acetazolamide decreased the Vmax of G-6-PD but not the Km and, therefore, appears to be a noncompetitive inhibitor of G-6-PD with an estimated Ki of 10(-4) M. The t-butyl analogue of acetazolamide, CL 13850, which is without CA inhibitory activity, had no measurable effect on G-6-PD activity. Accordingly, it is suggested the sulfonamide CA inhibitors may reduce JH by two modes of action, inhibition of CA and inhibition of G-6-PD.

Animals↗
PubMed2000

Xenopus NK cells identified by novel monoclonal antibodies.

Early-thymectomized (Tx) Xenopus frogs, which are permanently deficient in T cells, are used as a model sytem for the characterization of novel monoclonal antibodies (mAb) which identify candidate NK cells at the amphibian level of evolution. Hybridomas, generated from mice immunized with splenocytes from Tx Xenopus following B cell and thrombocyte depletion, were screened by flow cytometry. Three mAb (1F8, 4D4 and 1G5) were identified that stained increased proportions of splenocytes from Tx compared with control frogs. These mAb identified lymphoid populations from Xenopus spleen, liver and gut which, after 48 h culture in growth factor-rich medium, exhibited spontanous killing of MHC-deficient allotumor targets. mAb-defined splenocytes also rapidly induced apoptosis of such tumor targets. Dual color analysis confirmed that NK cells are neither T nor B cells. Cytospins of splenocytes isolated with anti-NK mAb revealed large lymphoid cells with distinct pseudopodia. Immunohistology indicated each anti-NK mAb routinely labeled cells within the gut epithelium but NK cells were difficult to visualize in spleen sections. Western blotting of spleen, liver and intestinal lysates subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis showed that 1G5 reacted strongly with protein bands of approximately 70 - 85 kDa, whereas mAb 1F8 and 4D4 stained less intensely, but identified similar protein bands.

Animals↗
PubMed2006

Long-term reactive transport modelling of stabilized/solidified waste: from dynamic leaching tests to disposal scenarios.

Environmental impact assessment of hazardous waste disposal relies, among others, on standardized leaching tests characterized by a strong coupling between diffusion and chemical processes. In that respect, this study shows that reactive transport modelling is a useful tool to extrapolate laboratory results to site conditions characterized by lower solution/solid (L/S) ratios, site specific geometry, infiltration, etc. A cement solidified/stabilized (S/S) waste containing lead is investigated as a typical example. The reactive transport model developed in a previous study to simulate the initial state of the waste as well as laboratory batch and dynamic tests is first summarized. Using the same numerical code (HYTEC), this model is then integrated to a simplified waste disposal scenario assuming a defective cover and rain water infiltration. The coupled evolution of the S/S waste chemistry and the pollutant plume migration are modelled assessing the importance of the cracking state of the monolithic waste. The studied configurations correspond to an undamaged and fully sealed system, a few main fractures between undamaged monoliths and, finally, a dense crack-network in the monoliths. The model considers the potential effects of cracking, first the increase of rain water and carbon dioxide infiltration and, secondly, the increase of L/S ratio and reactive surfaces, using either explicit fracture representation or dual porosity approaches.

Lead↗
PubMed1991

Applications of fluorescence in situ hybridization in biological dosimetry and detection of disease-specific chromosome aberrations.

Dual color FISH with whole chromosome and pan-centromere probes facilitates rapid detection of stable structural aberrations such as translocations. This approach should allow analysis of translocations for assessment of genetic damage at long times after exposure or as a result of chronic exposure during a long period of time. Multi-color FISH with locus specific probes allows assessment of the frequency of cells carrying specific aberrations known to be associated with tumorigenesis, analysis of the series of genetic changes that occur during tumor evolution and correlation between genotype and phenotype. The power of FISH for analysis of random and tumor related events will increase steadily as informative probes are developed during the course of the International Human Genome Project.

Chromosome Aberrations↗
PubMed1997

Evolutionary origin of cryptomonad microalgae: two novel chloroplast/cytosol-specific GAPDH genes as potential markers of ancestral endosymbiont and host cell components.

Cryptomonads are complex microalgae which share characteristics of chromophytes (chlorophyll c, extra pair of membranes surrounding the plastids) and rhodophytes (phycobiliproteins). Unlike chromophytes, however, they contain a small nucleus-like organelle, the nucleomorph, in the periplastidial space between the inner and outer plastid membrane pairs. These cellular characteristics led to the suggestion that cryptomonads may have originated via a eukaryote-eukaryote endosymbiosis between a phagotrophic host cell and a unicellular red alga, a hypothesis supported by rRNA phylogenies. Here we characterized cDNAs of the nuclear genes encoding chloroplast and cytosolic glyceraldehyde-3-phosphate dehydrogenases (GAPDH) from the two cryptomonads Pyrenomonas salina and Guillardia theta. Our results suggest that in cryptomonads the classic Calvin cycle GAPDH enzyme of cyanobacterial origin, GapAB, is absent and functionally replaced by a photosynthetic GapC enzyme of proteobacterial descent, GapC1. The derived GapC1 precursor contains a typical signal/transit peptide of complex structure and sequence signatures diagnostic for dual cosubstrate specificity with NADP and NAD. In addition to this novel GapC1 gene a cytosol-specific GapC2 gene of glycolytic function has been found in both cryptomonads showing conspicuous sequence similarities to animal GAPDH. The present findings support the hypothesis that the host cell component of cryptomonads may be derived from a phototrophic rather than a organotrophic cell which lost its primary plastid after receiving a secondary one. Hence, cellular compartments of endosymbiotic origin may have been lost or replaced several times in eukaryote cell evolution, while the corresponding endosymbiotic genes (e.g., GapC1) were retained, thereby increasing the chimeric potential of the nuclear genome.

Amino Acid Sequence↗
PubMed2000

Comparative immunocytochemical study of FMRFamide neuronal system in the brain of Danio rerio and Acipenser ruthenus during development.

The distribution of FMRFamide-like immunoreactive (ir) neurons and fibers was investigated in the central nervous system of developing zebrafish and juvenile sturgeon (sterlet). Adult zebrafish was also studied. In zebrafish embryos FMRFamide-ir elements first appeared 30 h post-fertilization (PF). Ir somata were located in the olfactory placode and in the ventral diencephalon. FMRFamide-ir fibers originating from diencephalic neurons were found in the ventral telencephalon and in ventral portions of the brainstem. At 48 h PF, the ir perikarya in the olfactory placode displayed increased immunoreactivity and stained fibers emerged from the somata. At 60 h PF, bilaterally, clusters of FMRFamide-ir neurons were found along the rostro-caudal axis of the brain, from the olfactory placode to rostral regions of the ventro-lateral telencephalon. At 60 h PF, numerous ir fibers appeared in the dorsal telencephalon, optic lobes, optic nerves, and retina. Except for ir fibers in the hypophysis at the age of 72 h PF, and a few ir cells in the nucleus olfacto-retinalis (NOR) at the age of 2 months PF, no major re-organization was noted in subsequent ontogenetic stages. The number of stained NOR neurons increased markedly in sexually mature zebrafish. In adult zebrafish, other ir neurons were located in the dorsal zones of the periventricular hypothalamus and in components of the nervus terminalis. We are inclined to believe that neurons expressing FMRFamide originate in the olfactory placode and in the ventricular ependyma in the hypothalamus. On the same grounds, a dual origin of FMRFamide-ir neurons is inferred in the sturgeon, an ancestral bony fish: prior to the observation of ir cells in the nasal area and in the telencephalon stained neurons were noted in circumventricular hypothalamic regions.

Age Factors↗