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Biomedical subjects

Catherine Martin

Publications and source records attributed to Catherine Martin.

12 recordsLinked to original sources
PubMed2006

Depression, sensation seeking, and maternal smoking as predictors of adolescent cigarette smoking.

The purpose of this study was to examine maternal and adolescent depression, maternal and teen sensation seeking, and maternal smoking, and their associations with adolescent smoking. Data were collected from a sample of 47 male and 66 female adolescents (ages 11-18 years) and their mothers from three different health clinics. The findings indicated that maternal sensation seeking was linked indirectly with adolescent smoking through teen sensation seeking, both of which were significantly associated with teen smoking (beta = 0.29, p < 0.001 and beta = 0.32, p < 0.001, respectively). Teen depression was associated positively with teen smoking (beta = 0.24, p < 0.01) when controlling for sensation seeking behaviors. Maternal smoking was also directly linked to adolescent smoking (beta = 0.20, p < 0.05). These findings underscore a potentially important role of sensation seeking in the origins of adolescent smoking, and clarify pathways of influence with regard to maternal attitudes and behaviors in subsequent teenage nicotine use.

Adolescent↗
PubMed2006

Genome restructuring in mouse embryos during reprogramming and early development.

Although a growing number of studies investigates functional genome organization in somatic cell nuclei, it is largely unknown how mammalian genome organization is established during embryogenesis. To address this question, we investigated chromo center formation and the peculiar arrangements of chromosome domains in early mouse embryos. At the one-cell stage, we observed characteristic arrangements of chromosomes and chromo center components. Subsequently, starting with the burst of zygotic genome transcription major rearrangements led to the establishment of somatic type chromo centers with a defined spatio-temporal organization. These processes appeared to be completed at the blastocyst stage with the onset of cell differentiation. During the same developmental period, a fraction of pericentric heterochromatin that was late replicating in the first cycle underwent switches in replication timing, spatial organization and epigenetic marks. Cloning experiments revealed that the genome organization typical for more advanced stages was quickly reverted into the one-cell stage-specific form after nuclear transfer, supporting the idea that reprogramming associated genome remodeling in normal and cloned embryos is determined by cytoplasmic factors. Together, the results suggest that distinct but characteristic forms of nuclear genome organization are required for genome reprogramming in early embryos and for proper regulation of differential gene expression patterns at later stages.

Animals↗
PubMed2006

Can P-glycoprotein influence the bioavailability of iminosugar-based glucosylceramide synthase inhibitors?

Recently developed glucosylceramide synthase inhibitors with enhanced hydrophobicity display increased bioavailability in the central nervous system (CNS). Have these improvements come at a potential risk given that the improved glucosylceramide synthase inhibitors bear the hallmarks of P-glycoprotein substrates? This question warrants attention given the potential to induce adverse drug interactions or toxicity, if glucosylceramide synthase inhibitors are administered with other P-glycoprotein substrates. The aim of this study was to determine if glucosylceramide synthase inhibitors are substrates for the multidrug transporter P-glycoprotein. Direct measurements of glucosylceramide synthase inhibitors binding to P-glycoprotein were examined, as was their ability to modulate transport by the protein. The more hydrophobic glucosylceramide synthase inhibitors caused a reduction in drug binding to P-glycoprotein. However, the compounds did not achieve this by direct interaction with the protein, but through a general membrane perturbation. Furthermore, the alterations in drug-P-glycoprotein interaction did not manifest as altered cellular accumulation of glucosylceramide synthase inhibitors or altered efficacy to reduce cellular glycolipid levels. Consequently, P-glycoprotein expression will not contribute significantly to the pharmacokinetic profile of the iminosugar glucosylceramide synthase inhibitors.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2006

Architectural reorganization of the nuclei upon transfer into oocytes accompanies genome reprogramming.

The ability of cloned embryos to sustain full-term development depends on the ability of the recipient ooplasm to reprogram the donor cell genome. As the nuclear architecture has recently emerged as a key-factor in the regulation of gene expression, we questioned whether early embryos obtained from transfer of ES metaphasic chromosomes into mouse ooplasm would adopt the somatic or embryonic type of nuclear organization. We have particularly focused on the arrangement of chromosomal territories with respect to the nucleolar compartment, and the pericentric heterochromatin domains called chromocenters. We found that nuclear transfer triggers profound chromatin rearrangements including the dispersion of the donor cell chromocenters components. These rearrangements lead to a typical 1-cell pronuclear organization, namely a radial arrangement of the chromosome territories with centromeres attached to the nucleoli, which adopt the compact fibrillar structure of nucleolar precursor bodies (NPBs). Subsequently, during the second cycle, the cloned embryos undergo further reorganization with the establishment of new chromocenters, clustered in one part of the nucleus, as during normal embryogenesis. We could also establish that the adequate distribution of chromosomal territories at the pronuclear stage seems important for the development until blastocyst.

Animals↗
PubMed2005

[Reprogramming and epigenesis].

The fact that the nucleus of a differentiated somatic cell can be reprogrammed in order to sustain embryonic development is now well established. Experiments of somatic cell nuclear transfer (cloning) have proved that a foreign nucleus introduced into an enucleated oocyte can give rise to physiologically normal offsprings, with a normal lifespan. Such evidence of genome expression plasticity is also observed experimentally with heterokaryons, created by the fusion or the nuclear transfer between two somatic cells, where differentiated nuclei are able to express genes characteristic of the host cell. However, the epigenetic mechanisms that permit nuclear plasticity remain poorly understood. In this paper we present the main evidences showing important modifications of the large scale organisation of chromosomal domains and of the DNA methylation pattern upon nuclear transfer and during the first cleavages. These modifications of epigenetic marks, brought by an intimate contact between the chromatin and the recipient oocyte cytoplasmic factors, appear essential for further development. They are established over the first cell cycles of development. The onset of embryonic genome activation and the first cellular differentiation events that occur over the implantation period are two additional check-points of reprogramming that appear to be also highly dependent on epigenetic alterations. Beyond those stages, defective placental functions might be directly responsible for the fetal and postnatal physiopathologies frequently observed in cloned animals. No direct link between preimplantation reprogramming defaults, placental dysfunctions and low development to term has been established yet. The epigenetics studies which are now used to characterise loci specific and probably genotype dependent alterations in cloned animals of different species will provide invaluable help to define the role of epigenesis in the achievement of a developmental program.

Animals↗
PubMed2004

Preparation and characterization of 6-molybdocobaltate and 6-molybdoaluminate cobalt salts. Evidence of a new heteropolymolybdate structure.

Molybdenum and cobalt based heteropolyanions (HPAs) could be used as an alternative to the conventional ammonium heptamolybdate and cobalt nitrate starting materials for friendly environmental preparation of Co-Mo/Al2O3 hydrotreating catalysts. In this aim, cobalt salts of molybdocobaltate and molydboaluminate Anderson HPAs have been synthesized and characterized by TGA, XRD, XAS, and vibrational spectroscopies. The crystal structure refinement provided evidence for the formation of a new heteropolyoxomolybdate derived from the well-known Anderson structure.

Journal Article↗
PubMed2004

Comparative efficacy of novel platinum(IV) compounds with established chemotherapeutic drugs in solid tumour models.

Platinum(II)-based anticancer drugs are associated with high reactivity and thus a poor biological stability. The platinum(IV)-complexes display potential advantages due to their greater stability and bioreductive activation, thereby allowing a greater proportion of the drug to arrive at the target intact. All compounds tested were able to produce cytotoxicity in monolayer cell cultures, however, the potencies of platinum(IV) drugs were lower than that observed for the platinum(II) compounds or established organic chemotherapeutic agents. There was no significant alteration in the potency of platinum(II) or (IV) compounds to produce cytotoxicity in multicellular tumour spheroids (MCTS) compared to monolayer cultures. All the organic and platinum-based cytotoxic agents produced, to varying degrees, either a retardation or reduction in MCTS growth. Proliferating cells were restricted to the outer two to three cellular layers in intermediate (d=350 microm) and large (d=600 microm) MCTS. Regardless of MCTS size, drug treatment produced a larger and more widely distributed proliferating cell population, consistent with the recruitment of quiescent cells to the proliferating pool following cytotoxic damage. Histology indicated that the predominant morphological change was that of apoptosis, although there was some drug-dependent effects such as the metaphase arrest produced by vinblastine and chromatin dispersal to the periphery of nuclei produced by doxorubicin. In summary, whilst the platinum(IV) derivatives were able to produce cytotoxicity via apoptosis, the introduction of a stable axial group significantly retarded the rate at which this occurred.

Antineoplastic Agents↗
PubMed2004

Evaluation of the blood gas analyzer Gem PREMIER 3000.

During the past few decades, new technologies have allowed the fabrication of miniaturized sensors and the development of analyzers well designed for point-of-care testing (POCT). They combined the ease-of-use and portability required for POC with the accuracy and the reliability of traditional systems. Instrumentation Laboratory introduced the GEM Premier 3000, a compact and portable system to rapidly analyze pH, pCO2, PO2, Ca2+, Na2+, K+, lactate, glucose and hematocrit, from 135 microl of whole blood with a simple component: a cartridge, the GEM Premier Pak. The analytical performance was compared with the Radiometer ABL 725 instrument for blood gas/ electrolytes/metabolites, and for hematocrit with the centrifuged microhematocrit method. Aqueous quality control materials (Instrumentation Laboratory) were used for precision and recovery studies. The evaluation was performed according to the Valtec protocol, designed by the French Society of Clinical Biology, for imprecision, linearity and accuracy. With-in-run and between-run imprecisions for all the parameters gave good CV values. Linearity was good and results comparison showed close agreement with correlation coefficients between 0.91 and 0.99. The analyzer is very easy to use; the simplicity and the convenience of only one consumable make the GEM Premier 3000 very suitable for a STAT laboratory or for POCT.

Blood Gas Analysis↗
PubMed2003

Comprehensive approaches to school health promotion: how to achieve broader implementation?

The Health Promoting School (HPS) and Comprehensive School Health Program (CSHP) initiatives have been proposed as a means of going beyond some of the limitations associated with health promotion initiatives aimed at school-aged children. This involves moving beyond practices that rely mainly on classroom-based health education models, to a more comprehensive, integrated approach of health promotion that focuses both on child-youth attitudes and behaviors, and their environment. Despite the tremendous potential of these initiatives in terms of health and educational gains, only rarely are they actually put into practice. This article briefly reviews the features of these initiatives, as well as the extent of their implementation and current benefits. Against that backdrop, the authors identify some issues to consider and propose four conditions with a view to achieving broader practical application of these approaches. These issues, which are discussed from the standpoint of potential avenues of further study and courses of action, relate to the comprehensive, integrated nature of the intervention, the school/family/community partnership, political and financial support from policy makers, and, finally, evaluative research as a support to implementation.

Health Promotion↗
PubMedDate not supplied

The physiology of amylin and insulin: maintaining the balance between glucose secretion and glucose uptake.

Glucose homeostasis is accomplished through intricate, and arguably, elegant interactions among several organs and hormones. Historically, glucose homeostasis has been viewed somewhat narrowly--insulin from pancreatic beta cells regulated glucose disposal, while glucagon from pancreatic alpha [corrected] cells regulated glucose appearance during fasting states. But more recent characterization and understanding of the role of incretin hormones from the gut--notably, glucagon-like peptide 1 and gastric inhibitory polypeptide--and amylin from pancreatic beta cells has led to a more complete model of glucose homeostasis. Furthermore, availability of pharmacologic agents to replace, mimic, or enhance the actions of these hormones allows application of this more complete model of glucose homeostasis to the treatment of type 1 and type 2 diabetes. This article provides an overview of the role of the pancreatic hormone amylin in glucose homeostasis and of Pramlintide, a analogue of native amylin, recently approved as adjunct therapy to insulin in people with type 1 and type 2 diabetes.

Amyloid↗