In Vitro Selection of Mercury (II)- and Arsenic (V)-Dependent RNA-Cleaving DNAzymes

Abstract DNAzymes (or catalytic DNA) are cell-free biomolecular recognition tools with target recognition sequences for charged molecules such as metal ions, antibiotics, and pharmaceuticals. In this study, using in vitro selection, large populations (e.g., 1015) of random DNA sequences were used as the raw material for the selection of “catalytic or functional molecules” for Hg2+ and As5+. From a random pool of 45-nt (Pool-A) and 35-nt (Pool-B) templates, we isolated RNA-cleaving catalytic Hg2+- and As5+- active DNAzymes, respectively. After eight cycles of selection and amplification wihin Pool A, sequences were enriched with a 54% cleavage efficiency against Hg2+. Similarly, Pool B was found to catalyze ca. 18% cleavage efficiency against As5+ after 10 cycles of repeated selection and amplification. The M-fold software analysis resulted in sequences in the two active pools being dominated by AATTCCGTAGGTCCAGTG and ATCTCCTCCTGTTC functional motifs for Hg2+- and As5+-based catalysis, respectively. These DNAzymes were found to have higher activity in the presence of transition metal ions compared to alkaline earth metal ions. A maximum cleavage rate of 2.7 min−1 for Hg2+ was found to be highest in our study at a saturating concentration of 500 μM. Results demonstrate that DNAzymes are capable of selectively binding transition metal ions, and catalytic rates are at par with most Mg2+-dependent nucleic acid enzymes under similar conditions, and indicate their potential as metal species-specific biosensors.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63396/1/ees.2006.0026.pd

In Vitro Selection of Hg (II) and As (V)-Dependent RNA-Cleaving DNAzymes

DNAzymes (or catalytic DNA) are cell-free biomolecular recognition tools with target recognition sequences for charged molecules such as metal ions, antibiotics, and pharmaceuticals. In this study, using in vitro selection, large populations (e.g., 1015) of random DNA sequences were used as the raw material for the selection of "catalytic or functional molecules" for Hg2+ and As5+. From a random pool of 45-nt (Pool-A) and 35-nt (Pool-B) templates, we isolated RNA-cleaving catalytic Hg2+- and As5+-active DNAzymes, respectively. After eight cycles of selection and amplification wihin Pool A, sequences were enriched with a 54% cleavage efficiency against Hg2+. Similarly, Pool-B was found to catalyze ca. 18% cleavage efficiency against As5+ after 10 cycles of repeated selection and amplification. The M-fold software analysis resulted in sequences in the two active pools being dominated by "AATTCCGTAGGTCCAGTG" and "ATCTCCTCCTGTTC" functional motifs for Hg2+- and As5+-based catalysis, respectively. These DNAzymes were found to have higher activity in the presence of transition metal ions compared to alkaline earth metal ions. A maximum cleavage rate of 2.7 min−1 for Hg2+ was found to be highest in our study at a saturating concentration of 500 µM. The results demonstrate that DNAzymes are capable of selectively binding transition metal ions, and catalytic rates are at par with most Mg2+-dependent nucleic acid enzymes under similar conditions, and indicate their potential as metal-species specific biosensors.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63104/1/ees.2007.24.73.pd

Cu 2+ Removal and recovery by Spi SORB: batch stirred and up-flow packed bed columnar reactor systems

The biosorption of Cu 2+ by free and poly acrylamide gel (PAG) immobilized Spirulina platensis ( Spi SORB) was characterized under batch and continuous packed bed columnar reaction systems. The biosorption of Cu 2+ was shown to be highest at pH of 6.0 for both types of biomass. The PAG immobilization process did not interfere with the Cu 2+ binding sites present on biomass leading to cent percent (ca. 250 mg g −1 of dry biomass) retention of biosorption as compared to free cells. Transmission electron microscopy on Cu 2+ localization revealed that majority of metal is being sequestered by the cell wall only. The infrared spectrum of metal treated S. platensis biomass indicated the possible involvement of amide, amino, and carboxyl groups in metal binding. Up-flow packed bed columnar reactor containing 2.0 g of PAG immobilized S. platensis shown a maximum of 143-fold volume reduction factor at the residence time of 4.6 min for Cu 2+ alone and found to decrease dramatically when Zn 2+ is present in a bimetallic solution.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45868/1/449_2006_Article_49.pd

Modelling the impact and cost-effectiveness of the HIV intervention programme amongst commercial sex workers in Ahmedabad, Gujarat, India.

BACKGROUND: Ahmedabad is an industrial city in Gujarat, India. In 2003, the HIV prevalence among commercial sex workers (CSWs) in Ahmedabad reached 13.0%. In response, the Jyoti Sangh HIV prevention programme for CSWs was initiated, which involves outreach, peer education, condom distribution, and free STD clinics. Two surveys were performed among CSWs in 1999 and 2003. This study estimates the cost-effectiveness of the Jyoti Sangh HIV prevention programme. METHODS: A dynamic mathematical model was used with survey and intervention-specific data from Ahmedabad to estimate the HIV impact of the Jyoti Sangh project for the 51 months between the two CSW surveys. Uncertainty analysis was used to obtain different model fits to the HIV/STI epidemiological data, producing a range for the HIV impact of the project. Financial and economic costs of the intervention were estimated from the providers perspective for the same time period. The cost per HIV-infection averted was estimated. RESULTS: Over 51 months, projections suggest that the intervention averted 624 and 5,131 HIV cases among the CSWs and their clients, respectively. This equates to a 54% and 51% decrease in the HIV infections that would have occurred among the CSWs and clients without the intervention. In the absence of intervention, the model predicts that the HIV prevalence amongst the CSWs in 2003 would have been 26%, almost twice that with the intervention. Cost per HIV infection averted, excluding and including peer educator economic costs, was USD 59 and USD 98 respectively. CONCLUSION: This study demonstrated that targeted CSW interventions in India can be cost-effective, and highlights the importance of replicating this effort in other similar settings.Published versio

Etätyön vaikutus työhyvinvointiin aikuissosiaalityössä

Etätyön tekemisen määrä on lisääntynyt merkittävästi viime vuosina ja monelle etänä työskentely saattoi olla täysin vieras käsite. Siirtyminen etätyöhön edellytti erilaisia laitteita ja toimivia yhteyksiä, mutta kaiken tämän ohella työntekijöiden työhyvinvointi saattoi helposti unohtua. Opinnäytetyön tavoitteena oli lisätä työelämäedustajan tietoa työntekijöidensä kokemuksista ja kehittää työtä sen pohjalta. Työn teoreettinen viitekehys on rakentunut aiheen keskeisten käsitteiden pohjalta, hyödyntäen erilaisia tietolähteitä kirjallisuudesta. Viitekehyksessä keskityttiin esimerkiksi aikuissosiaalityöhön, työhyvinvointiin, työn kuormittavuuteen sekä etätyöhön itsessään. Lähteenä on käytetty myös järjestöjen ja ministeriön materiaaleja, kuten Suomen sosiaali- ja terveysministeriön sekä Työturvallisuuskeskuksen aineistoa työhyvinvointiin ja työn kuormitukseen liittyen. Opinnäytetyön tarkoituksena oli selvittää työntekijöiden kokemuksia etätyön vaikutuksista työhyvin-vointiin eräässä Keski-Uudenmaan aikuissosiaalityön yksikössä. Tutkimuskysymyksenä oli: Miten etätyö on vaikuttanut työhyvinvointiin aikuissosiaalityössä? Opinnäytetyö oli laadullinen tutkielma, jossa aineistonkeruumenetelmänä käytettiin teemahaastatteluja. Haastattelut toteutettiin eräässä Keski-Uudenmaan alueen aikuissosiaalityön yksikössä. Haastatteluihin osallistui yhteensä seitsemän henkilöä, jotka toimivat sosiaaliohjaajina sekä sosiaalityöntekijöinä. Osa haastatteluista toteutettiin paikan päällä ja osa Teamsin kautta. Aineiston analyysimenetelmänä käytettiin induktiivista sisällönanalyysiä. Tulosten perusteella yksikössä käytössä ollut hybridimalli oli selkeästi vaikuttanut työntekoon. Arki ja työelämä oli helpompi sovittaa yhteen, samalla kun etänä työskennellessä työskentely tehokkuus lisääntyi. Etätyö kuitenkin edellyttää työntekijöiltä itseltään enemmän aktiivisuutta ja tiedostamista omaa työntekoaan kohtaan. Positiiviset vaikutukset näyttäytyivät työajan joustamisena, tehokkuuden lisääntymisenä sekä työyhteisön merkityksen korostumisena. Työergonomiaa, taukojen pitämiseen ja työn rajaamiseen täytyy keskittyä ja kiinnittää huomiota eri tavalla kuin toimistolla ollessa. Myös työyhteisön merkitys ja esihenkilön aktiivinen osallistuminen nousivat esille. Työyhteisö edistää ja on tärkeä osa yksilön työhyvinvointia ja sen merkitys korostuu, kun tehdään paljon yksin töitä kotoa. Jatkotutkimusideana tähän opinnäytetyöhön liittyen voisi tutkia vielä, miten työhyvinvointia on lähdetty myöhemmin kehittämään

Does scale matter? The costs of HIV-prevention interventions for commercial sex workers in India.

OBJECTIVE: To explore how the scale of a project affects both the total costs and average costs of HIV prevention in India. METHODS: Economic cost data and measures of scale (coverage and service volume indicators for number of cases of sexually transmitted infections (STIs) referred, number of STIs treated, condoms distributed and contacts made with target groups) were collected from 17 interventions run by nongovernmental organizations aimed at commercial sex workers in southern India. Nonparametric methods and regression analyses were used to look at the relationship between total costs, unit costs and scale. FINDINGS: Coverage varied from 250 to 2008 sex workers. Annual costs ranged from US$11 274 to US$ 52 793. The median cost per sex worker reached was US$19.21 (range = US$ 10.00-51.00). The scale variables explain more than 50% of the variation in unit costs for all of the unit cost measures except cost per contact. Total costs and unit costs have non-linear relationships to scale. CONCLUSION: Average costs vary with the scale of the project. Estimates of resource requirements based on a constant average cost could underestimate or overestimate total costs. The results highlight the importance of improving scale-specific cost information for planning

Does scale matter? The costs of HIV-prevention interventions for commercial sex workers in India

OBJECTIVE: To explore how the scale of a project affects both the total costs and average costs of HIV prevention in India. METHODS: Economic cost data and measures of scale (coverage and service volume indicators for number of cases of sexually transmitted infections (STIs) referred, number of STIs treated, condoms distributed and contacts made with target groups) were collected from 17 interventions run by nongovernmental organizations aimed at commercial sex workers in southern India. Nonparametric methods and regression analyses were used to look at the relationship between total costs, unit costs and scale. FINDINGS: Coverage varied from 250 to 2008 sex workers. Annual costs ranged from US$11 274 to US$ 52 793. The median cost per sex worker reached was US$19.21 (range = US$ 10.00-51.00). The scale variables explain more than 50% of the variation in unit costs for all of the unit cost measures except cost per contact. Total costs and unit costs have non-linear relationships to scale. CONCLUSION: Average costs vary with the scale of the project. Estimates of resource requirements based on a constant average cost could underestimate or overestimate total costs. The results highlight the importance of improving scale-specific cost information for planning

Growth of <i>Desulfovibrio vulgaris</i> When Respiring U(VI) and Characterization of Biogenic Uraninite

The capacity of <i>Desulfovibrio vulgaris</i> to reduce U­(VI) was studied previously with nongrowth conditions involving a high biomass concentration; thus, bacterial growth through respiration of U­(VI) was not proven. In this study, we conducted a series of batch tests on U­(VI) reduction by <i>D. vulgaris</i> at a low initial biomass (10 to 20 mg/L of protein) that could reveal biomass growth. <i>D. vulgaris</i> grew with U­(VI) respiration alone, as well as with simultaneous sulfate reduction. Patterns of growth kinetics and solids production were affected by sulfate and Fe²⁺. Biogenic sulfide nonenzymatically reduced 76% of the U­(VI) and greatly enhanced the overall reduction rate in the absence of Fe²⁺ but was rapidly scavenged by Fe²⁺ to form FeS in the presence of Fe²⁺. Biogenic U solids were uraninite (UO₂) nanocrystallites associated with 20 mg/g biomass as protein. The crystallite thickness of UO₂ was 4 to 5 nm without Fe²⁺ but was <1.4 nm in the presence of Fe²⁺, indicating poor crystallization inhibited by adsorbed Fe²⁺ and other amorphous Fe solids, such as FeS or FeCO₃. This work fills critical gaps in understanding the metabolic utilization of U by microorganisms and formation of UO₂ solids in bioremediation sites