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Nucleotide Excision Repair in Caenorhabditis elegans
Hannes Lans,Wim Vermeulen
Molecular Biology International , 2011, DOI: 10.4061/2011/542795
Abstract: Nucleotide excision repair (NER) plays an essential role in many organisms across life domains to preserve and faithfully transmit DNA to the next generation. In humans, NER is essential to prevent DNA damage-induced mutation accumulation and cell death leading to cancer and aging. NER is a versatile DNA repair pathway that repairs many types of DNA damage which distort the DNA helix, such as those induced by solar UV light. A detailed molecular model of the NER pathway has emerged from in vitro and live cell experiments, particularly using model systems such as bacteria, yeast, and mammalian cell cultures. In recent years, the versatility of the nematode C. elegans to study DNA damage response (DDR) mechanisms including NER has become increasingly clear. In particular, C. elegans seems to be a convenient tool to study NER during the UV response in vivo, to analyze this process in the context of a developing and multicellular organism, and to perform genetic screening. Here, we will discuss current knowledge gained from the use of C. elegans to study NER and the response to UV-induced DNA damage. 1. DNA Damage Response Mechanisms To preserve and faithfully transmit DNA to the next generation, cells are equipped with a variety of DNA repair pathways and associated DNA damage responses, collectively referred to as the DNA damage response (DDR). DNA is continuously damaged by environmental and metabolism-derived genotoxic agents. It is vital for cells and organisms to properly cope with DNA damage, because unrepaired damage can give rise to mutation and cell death. The importance of the DDR is illustrated by several human cancer prone and/or progeroid hereditary diseases, which are based on defects in the DDR. Over the last decades, a wealth of information on the molecular mechanism of different repair pathways has been gathered from detailed in vitro and live cell studies. Currently, this acquired knowledge is being used to develop therapeutic strategies to treat patients suffering from the consequences of unrepaired DNA damage, such as cancer and aging [1]. Damage is repaired by different DNA repair pathways depending on the type of DNA lesion, genomic location, and the cell cycle phase (for reviews see [2–4]). Lesions originating from different genotoxic sources can range from small base modifications to double-strand breaks. Small base modifications, such as oxidative lesions which do not substantially distort the double helix, are repaired by base excision repair (BER). BER removes single or several bases and repairs the gap by DNA synthesis. Bigger
ATP-dependent chromatin remodeling in the DNA-damage response
Hannes Lans, Jurgen A Marteijn, Wim Vermeulen
Epigenetics & Chromatin , 2012, DOI: 10.1186/1756-8935-5-4
Abstract: All living organisms depend on faithful preservation and transmission of genetic information to the next generation. Genetic information is stored within DNA, which is embedded in a dynamic nucleoprotein complex, called chromatin. The integrity of DNA is inescapably and continuously threatened by spontaneous and induced alterations to its basic structure. DNA itself is unstable and undergoes hydrolysis, which creates abasic sites and causes deamination [1]. Furthermore, cellular metabolic processes such as oxidative respiration produce oxygen radicals and other reactive molecules, which damage DNA [2]. Finally, exposure to environmental sources such as solar UV irradiation, × radiation, and numerous chemicals induces DNA injuries.DNA damage interferes with vital processes such as transcription and replication, which may cause cells to die or senesce, thus contributing to aging [3]. Replication of damaged DNA templates severely affects the fidelity of the polymerases, and may result in permanent mutations or chromosomal aberrations, which are at the basis of malignant transformation. Genetic erosion and its consequences are neutralized by a variety of DNA repair and associated DNA-damage signaling pathways, collectively called the DNA-damage response (DDR) [3-6]. In this review, we will focus on three repair pathways which are among the best characterized with regard to their repair mechanisms and interactions with chromatin: nucleotide excision repair (NER), which removes helix-distorting intra-strand lesions, and homologous recombination (HR) and non-homologous end-joining (NHEJ), both of which repair double-strand breaks (DSBs).All DNA-associated processes, such as transcription, replication, recombination, and DNA repair, are for a large part regulated by the chromatin structure [7,8]. Because this nucleoprotein complex limits the ability of other proteins to interact with DNA, the chromatin structure needs to be modified to facilitate efficient access to DNA. In
Involvement of Global Genome Repair, Transcription Coupled Repair, and Chromatin Remodeling in UV DNA Damage Response Changes during Development
Hannes Lans ,Jurgen A. Marteijn,Bj?rn Schumacher,Jan H. J. Hoeijmakers,Gert Jansen,Wim Vermeulen
PLOS Genetics , 2010, DOI: 10.1371/journal.pgen.1000941
Abstract: Nucleotide Excision Repair (NER), which removes a variety of helix-distorting lesions from DNA, is initiated by two distinct DNA damage-sensing mechanisms. Transcription Coupled Repair (TCR) removes damage from the active strand of transcribed genes and depends on the SWI/SNF family protein CSB. Global Genome Repair (GGR) removes damage present elsewhere in the genome and depends on damage recognition by the XPC/RAD23/Centrin2 complex. Currently, it is not well understood to what extent both pathways contribute to genome maintenance and cell survival in a developing organism exposed to UV light. Here, we show that eukaryotic NER, initiated by two distinct subpathways, is well conserved in the nematode Caenorhabditis elegans. In C. elegans, involvement of TCR and GGR in the UV-induced DNA damage response changes during development. In germ cells and early embryos, we find that GGR is the major pathway contributing to normal development and survival after UV irradiation, whereas in later developmental stages TCR is predominantly engaged. Furthermore, we identify four ISWI/Cohesin and four SWI/SNF family chromatin remodeling factors that are implicated in the UV damage response in a developmental stage dependent manner. These in vivo studies strongly suggest that involvement of different repair pathways and chromatin remodeling proteins in UV-induced DNA repair depends on developmental stage of cells.
Comparison of plants used for skin and stomach problems in Trinidad and Tobago with Asian ethnomedicine
Cheryl Lans
Journal of Ethnobiology and Ethnomedicine , 2007, DOI: 10.1186/1746-4269-3-3
Abstract: Trinidad and Tobago is one country consisting of two adjacent islands located just northeast of the Venezuelan coast with a combined area of 5070 km2 [1]. The human population of 1.25 million is multi-ethnic, multi-religious and multicultural and increases at 1% annually. In Trinidad, the major population centres are concentrated along the west coast and along an east-west transportation corridor in the north of the island [1].The multi-ethnic population of Trinidad and Tobago is reflected in its folk medicinal use. Previous research has indicated that the folk medicines used by hunters are derived from ancient Amerindian practices [2]. This paper will continue to explore the cultural origins of Caribbean folk medicine by investigating the contribution of the Chinese to Caribbean folk medicine. Chinese medicine has been described as a complex and holistic system of medical practice with its own philosophy, diagnosis, treatment systems and pharmacology which also includes acupuncture, moxibustion and Qi Gong. However in this paper I will focus on 'Ben Cao' (Herbalism) [3].The Chinese were the first Asian immigrants, arriving before the original East Indians who arrived in 1845. Chinese Tartars (192 men and one woman) were brought to Trinidad in the fall of 1806. These men from Macao, Penang and Canton were brought to cultivate tea but most were dissatisfied with local conditions and returned on the same ship [4,5]. The twenty-three who stayed made a living as entrepreneurs (butchers, shopkeepers, carpenters and market gardeners) and creolised (integrated into the local population).Prominent sugarcane planters believed that the emancipation of Caribbean slaves in 1838 would create a labour shortage. In the 1840s, the British "opened" a labor market of displaced or impoverished peasantry in southern China to fill this shortage and 2,500 mainly-male Chinese were brought legitimately to Trinidad as indentured workers, or were 'shanghaied' (abducted by European traders) [
Ethnomedicines used in Trinidad and Tobago for reproductive problems
Cheryl Lans
Journal of Ethnobiology and Ethnomedicine , 2007, DOI: 10.1186/1746-4269-3-13
Abstract: Thirty respondents, ten of whom were male were interviewed from September 1996 to September 2000. The respondents were obtained by snowball sampling, and were found in thirteen different sites, 12 in Trinidad (Paramin, Talparo, Sangre Grande, Mayaro, Carapichaima, Kernahan, Newlands, Todd's Road, Arima, Guayaguayare, Santa Cruz, Port of Spain and Siparia) and one in Tobago (Mason Hall). Snowball sampling was used because there was no other means of identifying respondents and to cover the entire islands. The validation of the remedies was conducted with a non-experimental method.Plants are used for specific problems of both genders. Clusea rosea, Urena sinuata and Catharanthus roseus are used for unspecified male problems. Richeria grandis and Parinari campestris are used for erectile dysfunction.Ageratum conyzoides, Scoparia dulcis, Cucurbita pepo, Cucurbita maxima, Gomphrena globosa and Justicia pectoralis are used for prostate problems.The following plants are used for childbirth and infertility: Mimosa pudica, Ruta graveolens,Abelmoschus moschatus, Chamaesyce hirta, Cola nitida, Ambrosia cumanenesis, Pilea microphylla, Eryngium foetidum, Aristolochia rugosa, Aristolochia trilobata, Coleus aromaticus, Laportea aestuans and Vetiveria zizanioides.The following plants are used for menstrual pain and unspecified female complaints:Achyranthes indica, Artemisia absinthium, Brownea latifolia, Eleutherine bulbosa, Hibiscus rosa-sinensis, Eupatorium macrophyllum, Justicia secunda, Parthenium hysterophorus, Wedelia trilobata, Abelmoschus moschatus, Capraria biflora, Cordia curassavica, Croton gossypifolius, Entada polystachya, Leonotis nepetaefolia, Eryngium foetidum, Aristolochia rugosa, Aristolochia trilobata and Ambrosia cumanenesis.Native Caribbean plants have been less studied that those from Africa, India and Europe. Chamaesyce hirta has scientific support but as a diuretic. Other plants with level 3 validity for reproductive issues are: Achyranthes indica, Coleus ar
Organic parasite control for poultry and rabbits in British Columbia, Canada
Cheryl Lans, Nancy Turner
Journal of Ethnobiology and Ethnomedicine , 2011, DOI: 10.1186/1746-4269-7-21
Abstract: Consumers, butchers and restaurant-owners are increasingly demanding that meat animals be reared in environmentally-sensitive ways that also take animal welfare concerns into consideration (e.g. access to pasture); these organic farming management practices also improve meat quality [1-5]. The meat from poultry and rabbits is more efficient to produce in terms of land use, feed and water use than beef and pork and thus produces a lower environmental impact [6-10]. Some consumers are also concerned about chemical residues (like flubendazole) in meat [11,12]. The access to pasture demanded by animal welfare agents increases the need for parasite control in food animals [11,13]. Organic agriculture allows a restricted number of substances to be used for pest control.Some conventional livestock farmers add subclinical levels of antibiotics to the animal feed of millions of food animals as growth promoters [14]. Some of these antibiotics are not absorbed and are excreted in manure which is then applied as a fertilizer to food crops. As much as 387 g of chlortetracycline and 202 g of tylosin per hectare is estimated to be added to the soil with the application of pig manure. Greenhouse studies conducted on corn (Zea mays L.), green onion (Allium cepa L.), and cabbage (Brassica oleracea L. Capitata group) showed that all three crops absorbed chlortetracycline from pig manure but tylosin was not absorbed [14]. Botanical and mineral products used for animal health are less likely to become soil contaminants than chlortetracycline since they are natural products.Extracts and essential oils of various plants such as Rosmarinus officinalis L. (rosemary), Mentha piperita L. and M. virdis (L.) L.(mints), Artemisia absinthium L. (absinthium, or wormwood), Chenopodium ambrosioides L. (epazote), Thymus vulgaris L. (thyme) and Origanum vulgare L. (oregano) have potential for use as parasite controls because they have insecticidal activity. For example, essential oils of Melissa offic
Ethnomedicines used in Trinidad and Tobago for urinary problems and diabetes mellitus
Cheryl A Lans
Journal of Ethnobiology and Ethnomedicine , 2006, DOI: 10.1186/1746-4269-2-45
Abstract: A non-experimental validation was conducted on the plants used for urinary problems and diabetes mellitus: This is a preliminary step to establish that the plants used are safe or effective, to help direct clinical trials, and to inform Caribbean physicians of the plants' known properties to avoid counter-prescribing.The following plants are used to treat diabetes: Antigonon leptopus, Bidens alba, Bidens pilosa, Bixa orellana, Bontia daphnoides, Carica papaya, Catharanthus roseus, Cocos nucifera, Gomphrena globosa, Laportea aestuans, Momordica charantia, Morus alba, Phyllanthus urinaria and Spiranthes acaulis. Apium graviolens is used as a heart tonic and for low blood pressure. Bixa orellana, Bontia daphnoides, Cuscuta americana and Gomphrena globosa are used for jaundice. The following plants are used for hypertension: Aloe vera, Annona muricata, Artocarpus altilis, Bixa orellana, Bidens alba, Bidens pilosa, Bonta daphnoides, Carica papaya, Cecropia peltata, Citrus paradisi, Cola nitida, Crescentia cujete, Gomphrena globosa, Hibiscus sabdariffa, Kalanchoe pinnata, Morus alba, Nopalea cochinellifera, Ocimum campechianum, Passiflora quadrangularis, Persea americana and Tamarindus indicus.The plants used for kidney problems are Theobroma cacao, Chamaesyce hirta, Flemingia strobilifera, Peperomia rotundifolia, Petiveria alliacea, Nopalea cochinellifera, Apium graveolens, Cynodon dactylon, Eleusine indica, Gomphrena globosa, Pityrogramma calomelanos and Vetiveria zizanioides. Plants are also used for gall stones and for cooling.Chamaesyce hirta, Cissus verticillata, Kalanchoe pinnata, Peperomia spp., Portulaca oleraceae, Scoparia dulcis, and Zea mays have sufficient evidence to support their traditional use for urinary problems, "cooling" and high cholesterol.Eggplant extract as a hypocholesterolemic agent has some support but needs more study. The plants used for hypertension, jaundice and diabetes that may be safe and justify more formal evaluation are Annona squamos
HALLAZGO DE MERCURIO EN PECES DE LA CIéNAGA DE AYAPEL, CóRDOBA, COLOMBIA
Marrugo,José; Lans,Edineldo; Benítez,Luis;
Revista MVZ Córdoba , 2007,
Abstract: objetive. to establish total mercury (hg-t) concentrations in some fishes species in the ayapel marsh (colombia). materials and methods. sampling was conducted from july 2004 to june 2005, including both the dry and rainy seasons. hg-t was analized by cold vapor atomic absorption spectroscopy after acid digestion. results. the highest concentrations in hg-t were observed for analized samples of the carnivorous specie ageneiosus caucanus (0.504±0.103 mg hg kg-1 fresh weight), and the lowest concentrations in the iliophagus specie prochilodus magdalenae (0.130±0.056 mg hg kg-1 fresh wt). the highest hg-t concentrations were found in the samples of the dry season. the hg-t mean levels for fish samples did not exceed the human limit consumption level according to the world health organization (who, 0.5 mg hg kg-1 fresh weight). conclusions. the risk assessment based on the hazard index suggested that the consumption of 0.12 kg per day of fish (mainly carnivorous) could increase the risk of mercury poisoning in the local population.
HALLAZGO DE MERCURIO EN PECES DE LA CIéNAGA DE AYAPEL, CóRDOBA, COLOMBIA
José Marrugo,Edineldo Lans,Luis Benítez
Revista MVZ Córdoba , 2007,
Abstract: Objetivo. Determinar las concentraciones de mercurio total (Hg-T) en algunasespecies de peces de la ciénaga de Ayapel (Colombia). Materiales y métodos. Losmuestreos fueron realizados desde Julio de 2004 a Junio de 2005, incluyendo lasépocas seca y lluviosa. Las muestras fueron analizadas por espectrometría deabsorción atómica por vapor frío después de digestión ácida. Resultados. Lasconcentraciones más altas de Hg-T se observaron para las muestras analizadas dela especie carnívora Ageneiosus caucanus (0.504±0.103 mg Hg kg-1 peso fresco), ylas menores concentraciones en la especie Iliófaga Prochilodus magdalenae(0.130±0.056 mg Hg kg-1 peso fresco). Las concentraciones más altas fueronencontradas en las muestras de la época seca. Los niveles promedio de Hg-T en lasmuestras de peces no excedieron el límite para consumo humano establecido por laOrganización Mundial de la Salud (OMS, 0.5 mg Hg Kg-1 peso fresco). Conclusiones.La evaluación del riesgo basado en el índice de peligrosidad sugiere que el consumode 0.12 kg de pescado por día en la población humana (principalmente carnívoros)podría incrementar el riesgo de envenenamiento por mercurio en la población local.
Mit Nachdruck gegen den Verleger. Alte Allianzen und neue Positionen am literarischen Markt
Hannes Fischer
Libreas : Library Ideas , 2012,
Abstract:
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