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  • Evaluation of utilisation of the Prevention of Mother-to-Child Transmission of HIV Programme in Central province, Kenya

    Ngugi, Catherine Njeri (2013)

    Masters thesis
    The University of Auckland Library

    Background: The PMTCT HIV programme has been one of the most successful HIV preventive interventions towards HIV-free future generations. However, even though the programme is virtually effective in developed countries, many developing countries are reporting child HIV infections due to the MTCT. The programme has existed in Kenya for more than a decade, yet in 2011, 12,894children were HIV infected due to MTCT Objective: To evaluate the PMTCT programme, especially the HIV testing from the antenatal period to the postnatal period among expectant parents attending Nyeri Provincial General Hospital in Central Province, Kenya. Design: Retrospective analysis of the hospital registers. Methods: Three hospital registers were analysed for the period from July 2009 to September 2012. The registers were for antenatal, intrapartum and postnatal care respectively. Each register documented the utilisation of PMTCT services by the expectant parents. Descriptive and inferential statistics were produced to analyse data from the registers. Results: The PMTCT services utilisation was sub-optimal. Of the 504 expectant mothers who attended the antenatal clinic, 59.9% came once, 80.4% had their first visit in the third trimester (between weeks 28 and 40) and only 6.9% were accompanied by their partners. All the women were HIV tested in their first visit but only 12.1% were rescreened after three months, and only 3.8% had been tested prior to the current pregnancy (p=0.000). No expectant mother was tested for HIV intrapartum or postpartum. The children of the 504 mothers who were HIV tested were those whose parent/s were known to be HIV positive or who had presented to a child welfare clinic with recurring symptoms suggestive of a failing immune system. Conclusion: Public health programs need to strengthen the PMTCT and HIV prevention programmes to ensure that HIV testing preconception and in pregnancy is fully implemented and strengthened, alongside continued education of the public through community programmes and the media. To avert further horizontal and vertical transmission of HIV, there is a need to address urgently the identified missed opportunities in the PMTCT program. These programmatic challenges require health system redesign and strengthening, resource allocation, addressing research gaps and reassessing the current PMTCT policies.

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  • Investigating diet as the source of tetrodotoxin in Pleurobranchaea maculata

    Khor, Serena; Wood, Susanna A.; Salvitti, Lauren R.; Taylor, David I.; Adamson, Janet E.; McNabb, Paul; Cary, S. Craig (2014)

    Journal article
    University of Waikato

    The origin of tetrodotoxin (TTX) is highly debated; researchers have postulated either an endogenous or exogenous source with the host accumulating TTX symbiotically or via food chain transmission. The aim of this study was to determine whether the grey side-gilled sea slug (Pleurobranchaea maculata) could obtain TTX from a dietary source, and to attempt to identify this source through environmental surveys. Eighteen non-toxic P. maculata were maintained in aquariums and twelve were fed a TTX-containing diet. Three P. maculata were harvested after 1 h, 24 h, 17 days and 39 days and TTX concentrations in their stomach, gonad, mantle and remaining tissue/fluids determined using liquid chromatography-mass spectrometry. Tetrodotoxin was detected in all organs/tissue after 1 h with an average uptake of 32%. This decreased throughout the experiment (21%, 15% and 9%, respectively). Benthic surveys at sites with dense populations of toxic P. maculata detected very low or no TTX in other organisms. This study demonstrates that P. maculata can accumulate TTX through their diet. However, based on the absence of an identifiable TTX source in the environment, in concert with the extremely high TTX concentrations and short life spans of P. maculata, it is unlikely to be the sole TTX source for this species.

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  • Mathematical modelling of anoestrus in dairy cows and the linkage to nutrition

    Smith, JF; Soboleva, TK; Peterson, AJ; Pleasants, T; Chagas, LM; Burke, CR (2005-01-01)

    Conference paper
    Massey University

    Postpartum anoestrus is a major reproductive problem in New Zealand dairy cows and its duration is related to the nutrition levels both pre and post calving. However, the mechanistic details of this relationship are largely unknown. A better understanding of the interactions between nutritional status, and the levels of the reproductive hormones controlling follicle development and ovulation is needed. A mathematical model consisting of a set of interactive nonlinear differential equations and describing the dynamics of the interactions among luteinising hormone (LH), follicle stimulating hormone (FSH) and oestradiol was developed. The model depicts oestradiol profiles generated by individual follicles from the first follicular wave after calving until ovulation, and changes in LH pulsatility leading to the first pre-ovulatory surge are also produced. The robustness of the model was ascertained from iterative processes, and it was also checked against existing experimental data so as to mimic observed changes in hormone levels. It was shown that two mathematical parameters which control: i) the speed of changes in the feedback of LH activity to oestradiol; and, ii) the sensitivity of the ovarian response to LH, have the greatest effect on duration of anoestrus.

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  • Identity Issues and Challenges Faced by Russian Immigrants in New Zealand

    Maydell, E; Wilson, MS (2009)

    Journal article
    Massey University

    Among the processes cosmopolitan societies undergo at the present moment, is the unprecedented increase in mass migration across cultures. What challenges are faced by both immigrants, who have to settle in novel socio-cultural environments, and by the host populations accepting them? The current qualitative study investigates the nature of identity construction among Russian-speaking immigrants in New Zealand, applying thematic analysis for the interpretation of the data collected via 23 in-depth interviews. Among the most common themes articulated by the participants was the feeling of identity loss. A taken-for-granted sense of identity, brought by the participants from their culture of origin, was not validated by their new society of residence, mostly due to the lack of appropriate cultural resources. The participants were faced with a challenge of re-constructing their old identity, or constructing a new one, utilising the available resources in the community around them. At the same time, there was a sub-group for whom this challenge brought the realisation that the nature of their identity is cosmopolitan, rather than located within any particular culture or geographical space

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  • On the road to diploidization? Homoeolog loss in independently formed populations of the allopolyploid Tragopogon miscellus (Asteraceae)

    Tate, Jennifer A.; Joshi, Prashant; Soltis, Kerry A.; Soltis, Pamela S.; Soltis, Douglas E. (2009-06-27)

    Journal article
    Massey University

    Background: Polyploidy (whole-genome duplication) is an important speciation mechanism, particularly in plants. Gene loss, silencing, and the formation of novel gene complexes are some of the consequences that the new polyploid genome may experience. Despite the recurrent nature of polyploidy, little is known about the genomic outcome of independent polyploidization events. Here, we analyze the fate of genes duplicated by polyploidy (homoeologs) in multiple individuals from ten natural populations of Tragopogon miscellus (Asteraceae), all of which formed independently from T. dubius and T. pratensis less than 80 years ago. Results: Of the 13 loci analyzed in 84 T. miscellus individuals, 11 showed loss of at least one parental homoeolog in the young allopolyploids. Two loci were retained in duplicate for all polyploid individuals included in this study. Nearly half (48%) of the individuals examined lost a homoeolog of at least one locus, with several individuals showing loss at more than one locus. Patterns of loss were stochastic among individuals from the independently formed populations, except that the T. dubius copy was lost twice as often as T. pratensis. Conclusion: This study represents the most extensive survey of the fate of genes duplicated by allopolyploidy in individuals from natural populations. Our results indicate that the road to genome downsizing and ultimate genetic diploidization may occur quickly through homoeolog loss, but with some genes consistently maintained as duplicates. Other genes consistently show evidence of homoeolog loss, suggesting repetitive aspects to polyploid genome evolution.

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  • Understanding the Relationship between Activity and Neighbourhoods (URBAN) Study: research design and methodology

    Badland, Hannah M.; Schofield, Grant M.; Witten, Karen; Schluter, Philip J.; Mavoa, Suzanne; Kearns, Robin A.; Hinckson, Erica A.; Oliver, Melody; Kaiwai, Hector; Jensen, Victoria G.; Ergler, Christina; McGrath, Leslie; McPhee, Julia (2009-07)

    Journal article
    Massey University

    Background: Built environment attributes are recognized as being important contributors to physical activity (PA) engagement and body size in adults and children. However, much of the existing research in this emergent public health field is hindered by methodological limitations, including: population and site homogeneity, reliance on self-report measures, aggregated measures of PA, and inadequate statistical modeling. As an integral component of multi-country collaborative research, the Understanding the Relationship between Activity and Neighbourhoods (URBAN) Study seeks to overcome these limitations by determining the strengths of association between detailed measures of the neighborhood built environment with PA levels across multiple domains and body size measures in adults and children. This article outlines the research protocol developed for the URBAN Study. Methods and design: The URBAN Study is a multi-centered, stratified, cross-sectional research design, collecting data across four New Zealand cities. Within each city, 12 neighborhoods were identified and selected for investigation based on higher or lower walkability and Maori demographic attributes. Neighborhoods were selected to ensure equal representation of these characteristics. Within each selected neighborhood, 42 households are being randomly selected and an adult and child ( where possible) recruited into the study. Data collection includes: objective and self-reported PA engagement, neighborhood perceptions, demographics, and body size measures. The study was designed to recruit approximately 2,000 adults and 250 children into the project. Other aspects of the study include photovoice, which is a qualitative assessment of built environment features associated with PA engagement, an audit of the neighborhood streetscape environment, and an individualized neighborhood walkability profile centered on each participant's residential address. Multilevel modeling will be used to examine the individual-level and neighborhood-level relationships with PA engagement and body size. Discussion: The URBAN Study is applying a novel scientifically robust research design to provide urgently needed epidemiological information regarding the associations between the built environment and health outcomes. The findings will contribute to a larger, international initiative in which similar neighborhood selection and PA measurement procedures are utilized across eight countries. Accordingly, this study directly addresses the international priority issues of increasing PA engagement and decreasing obesity levels.

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  • The influence of age and breed of cow on colostrum indicators of suckled beef calves

    Hickson, RE; Back, PJ; Martin, NP; Kenyon, PR; Morris, ST (2016-07-07)

    Conference paper
    Massey University

    false

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  • Testing the Effect of Metabolic Rate on DNA Variability at the Intra-Specific Level

    McGaughran, Angela; Holland, Barbara R. (2010-03-15)

    Journal article
    Massey University

    Funding: AM was supported by a New Zealand Tertiary Education Commission Top Achievers Doctoral Scholarship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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  • Impact of Genetic Background on Allele Selection in a Highly Mutable Candida albicans Gene, PNG2

    Zhang, Ningxin; Cannon, Richard D.; Holland, Barbara R.; Patchett, Mark L.; Schmid, Jan (2010-03-09)

    Journal article
    Massey University

    Formal Correction: This article has been formally corrected to address the following errors. 1. Figure 2 was not reproduced correctly due to a problem during generation of a postscript file submitted for production. Please view the correct figure here: http://www.plosone.org/corrections/pone.0009614.g002.cn.tif

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  • Does Viagra protect fetal lambs against maternal pregnancy toxaemia?

    Peterson, SW; Pain, SJ; McCoard, SA; Oliver, M; Baker, PB; Kenyon, PR; Blair, HT (2016-07-07)

    Journal article
    Massey University

    Poor fetal growth is commonly caused by placental insufficiency. In sheep, multiple fetuses have relatively small placentae with fewer cotyledons than singletons, limiting blood flow to the placenta, especially in late gestation when fetal growth rate is highest. Factors that reduce fetal growth, such as maternal genotype, nutrition, age, parity, fetal number, or environmental temperature, typically reduce placental size and are associated with lower rates of fetal oxygen and nutrient uptakes and placental blood flow (Reynolds & Redmer 2001). Further, circumstances that influence placental vascular development have a dramatic impact on fetal growth and development, and affect neonatal survival and growth (Borowicz et al. 2007; Satterfield et al, 2010). Sildenafil citrate (SC, trade names Viagra or Avigra) increases vasodilatation of uteroplacental vessels (Wareing et al. 2005) and may represent a novel therapy to improve fetal lamb growth. Sildenafil citrate has successfully increased birth weight in rodent models and singleton bearing ewes (Satterfield et al. 2010; Miller at al. 2009). There is no published information regarding the use of SC in multiple-bearing ewes. The objective of this trial was to determine if SC administration to triplet-bearing ewes in late gestation could increase lamb birth weight. In addition, the influence of SC on the incidence of pregnancy toxaemia is also reported here.

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  • Reproductive performance of singleton and twin female offspring born to ewe-lamb dams and mature adult dams

    Kenyon, PR

    Conference paper
    Massey University

    false

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  • Quantifying Risk Factors for Human Brucellosis in Rural Northern Tanzania

    Kunda, John; Fitzpatrick, Julie; French, Nigel; Kazwala, Rudovick; Kambarage, Dominic; Mfinanga, Godfrey S.; MacMillan, Alastair; Cleaveland, Sarah (2010-04-01)

    Journal article
    Massey University

    Funding: The study was funded by the Department for International Development of the UK through the Animal Health Programme. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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  • LineageSpecificSeqgen: generating sequence data with lineage-specific variation in the proportion of variable sites

    Grievink, Liat Shavit; Penny, David; Hendy, Mike D; Holland, Barbara R (2008-11-21)

    Journal article
    Massey University

    Background: Commonly used phylogenetic models assume a homogeneous evolutionary process throughout the tree. It is known that these homogeneous models are often too simplistic, and that with time some properties of the evolutionary process can change (due to selection or drift). In particular, as constraints on sequences evolve, the proportion of variable sites can vary between lineages. This affects the ability of phylogenetic methods to correctly estimate phylogenetic trees, especially for long timescales. To date there is no phylogenetic model that allows for change in the proportion of variable sites, and the degree to which this affects phylogenetic reconstruction is unknown. Results: We present LineageSpecificSeqgen, an extension to the seq-gen program that allows generation of sequences with both changes in the proportion of variable sites and changes in the rate at which sites switch between being variable and invariable. In contrast to seq-gen and its derivatives to date, we interpret branch lengths as the mean number of substitutions per variable site, as opposed to the mean number of substitutions per site (which is averaged over all sites, including invariable sites). This allows specification of the substitution rates of variable sites, independently of the proportion of invariable sites. Conclusion: LineageSpecificSeqgen allows simulation of DNA and amino acid sequence alignments under a lineage-specific evolutionary process. The program can be used to test current models of evolution on sequences that have undergone lineage-specific evolution. It facilitates the development of both new methods to identify such processes in real data, and means to account for such processes. The program is available at: http://awcmee.massey.ac.nz/downloads.htm.

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  • Elephant (Loxodonta africana) Home Ranges in Sabi Sand Reserve and Kruger National Park: A Five-Year Satellite Tracking Study

    Thomas, Bindi; Holland, John D.; Minot, Edward O. (2008-12-09)

    Journal article
    Massey University

    Funding: We gratefully acknowledge the financial support of the Institute of Natural Resources, Massey University. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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  • Using supernetworks to distinguish hybridization from lineage-sorting

    Holland, Barbara R.; Benthin, Steffi; Lockhart, Peter J.; Moulton, Vincent; Huber, Katharina T. (2008-07-14)

    Journal article
    Massey University

    Background: A simple and widely used approach for detecting hybridization in phylogenies is to reconstruct gene trees from independent gene loci, and to look for gene tree incongruence. However, this approach may be confounded by factors such as poor taxon-sampling and/or incomplete lineage-sorting. Results: Using coalescent simulations, we investigated the potential of supernetwork methods to differentiate between gene tree incongruence arising from taxon sampling and incomplete lineagesorting as opposed to hybridization. For few hybridization events, a large number of independent loci, and well-sampled taxa across these loci, we found that it was possible to distinguish incomplete lineage-sorting from hybridization using the filtered Z-closure and Q-imputation supernetwork methods. Moreover, we found that the choice of supernetwork method was less important than the choice of filtering, and that count-based filtering was the most effective filtering technique. Conclusion: Filtered supernetworks provide a tool for detecting and identifying hybridization events in phylogenies, a tool that should become increasingly useful in light of current genome sequencing initiatives and the ease with which large numbers of independent gene loci can be determined using new generation sequencing technologies.

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  • Egg Eviction Imposes a Recoverable Cost of Virulence in Chicks of a Brood Parasite

    Anderson, Michael G.; Moskát, Csaba; Bán, Miklós; Grim, Tomáš; Cassey, Philip; Hauber, Mark E. (2009-11-11)

    Journal article
    Massey University

    Background: Chicks of virulent brood parasitic birds eliminate their nestmates and avoid costly competition for foster parental care. Yet, efforts to evict nest contents by the blind and naked common cuckoo Cuculus canorus hatchling are counterintuitive as both adult parasites and large older cuckoo chicks appear to be better suited to tossing the eggs and young of the foster parents. Methodology/Principal Findings: Here we show experimentally that egg tossing imposed a recoverable growth cost of mass gain in common cuckoo chicks during the nestling period in nests of great reed warbler Acrocephalus arundinaceus hosts. Growth rates of skeletal traits and morphological variables involved in the solicitation of foster parental care remained similar between evictor and non-evictor chicks throughout development. We also detected no increase in predation rates for evicting nests, suggesting that egg tossing behavior by common cuckoo hatchlings does not increase the conspicuousness of nests. Conclusion: The temporary growth cost of egg eviction by common cuckoo hatchlings is the result of constraints imposed by rejecter host adults and competitive nestmates on the timing and mechanism of parasite virulence.

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  • Genomic and genetic analyses of diversity and plant interactions of Pseudomonas fluorescens

    Silby, Mark W.; Cerdeno-Tarraga, Ana M.; Vernikos, Georgios S.; Giddens, Stephen R.; Jackson, Robert W.; Preston, Gail M.; Zhang, Xue-Xian; Moon, Christina D.; Gehrig, Stefanie M.; Godfrey, Scott A. C.; Knight, Christopher G.; Malone, Jacob G.; Robinson, Zena; Spiers, Andrew J.; Harris, Simon; Challis, Gregory L; Yaxley, Alice M.; Harris, David; Seeger, Kathy; Murphy, Lee; Rutter, Simon; Squares, Rob; Quail, Michael A.; Saunders, Elizabeth; Mavromatis, Konstantinos; Brettin, Thomas S.; Bentley, Stephen D.; Hothersall, Joanne; Stephens, Elton; Thomas, Christopher M.; Parkhill, Julian; Levy, Stuart B.; Rainey, Paul B.; Thomson, Nicholas R. (2009-05-11)

    Journal article
    Massey University

    Background: Pseudomonas fluorescens are common soil bacteria that can improve plant health through nutrient cycling, pathogen antagonism and induction of plant defenses. The genome sequences of strains SBW25 and Pf0-1 were determined and compared to each other and with P. fluorescens Pf-5. A functional genomic in vivo expression technology (IVET) screen provided insight into genes used by P. fluorescens in its natural environment and an improved understanding of the ecological significance of diversity within this species. Results: Comparisons of three P. fluorescens genomes (SBW25, Pf0-1, Pf-5) revealed considerable divergence: 61% of genes are shared, the majority located near the replication origin. Phylogenetic and average amino acid identity analyses showed a low overall relationship. A functional screen of SBW25 defined 125 plant-induced genes including a range of functions specific to the plant environment. Orthologues of 83 of these exist in Pf0-1 and Pf-5, with 73 shared by both strains. The P. fluorescens genomes carry numerous complex repetitive DNA sequences, some resembling Miniature Inverted-repeat Transposable Elements (MITEs). In SBW25, repeat density and distribution revealed 'repeat deserts' lacking repeats, covering approximately 40% of the genome. Conclusions: P. fluorescens genomes are highly diverse. Strain-specific regions around the replication terminus suggest genome compartmentalization. The genomic heterogeneity among the three strains is reminiscent of a species complex rather than a single species. That 42% of plant-inducible genes were not shared by all strains reinforces this conclusion and shows that ecological success requires specialized and core functions. The diversity also indicates the significant size of genetic information within the Pseudomonas pan genome.

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  • Within and between Whorls: Comparative Transcriptional Profiling of Aquilegia and Arabidopsis

    Voelckel, Claudia; Borevitz, Justin O.; Kramer, Elena M.; Hodges, Scott A. (2010-03-23)

    Journal article
    Massey University

    Funding: This work was funded under a National Science Foundation grant to SA Hodges (http://www.nsf.gov/awardsearch/showAward.do?AwardNumber = 0412727). C Voelckel acknowledges funding from the Alexander von Humboldt Foundation through a Feodor Lynen Fellowship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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  • Does ewe nutrition during pregnancy affect the neonatal behaviour of twin-born lambs?

    Gronqvist, GV; Hickson, RE; Corner-Thomas, RA; Kenyon, PR; Stafford, KJ; Morris, ST (2016-01-01)

    Journal article
    Massey University

    false

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  • Respiratory symptoms in children living near busy roads and their relationship to vehicular traffic: results of an Italian multicenter study (SIDRIA 2)

    Migliore, Enrica; Berti, Giovanna; Galassi, Claudia; Pearce, Neil; Forastiere, Francesco; Calabrese, Roberto; Armenio, Lucio; Biggeri, Annibale; Bisanti, Luigi; Bugiani, Massimiliano; Cadum, Ennio; Chellini, Elisabetta; Dell'Orco, Valerio; Giannella, Gabriele; Sestini, Piersante; Corbo, Giuseppe; Pistelli, Riccardo; Viegi, Giovanni; Ciccone, Giovannino; SIDRIA-2 Collaborative Group (2009-06-18)

    Journal article
    Massey University

    Background: Epidemiological studies have provided evidence that exposure to vehicular traffic increases the prevalence of respiratory symptoms and may exacerbate pre-existing asthma in children. Self-reported exposure to road traffic has been questioned as a reliable measurement of exposure to air pollutants. The aim of this study was to investigate whether there were specific effects of cars and trucks traffic on current asthma symptoms (i.e. wheezing) and cough or phlegm, and to examine the validity of self-reported traffic exposure. Methods: The survey was conducted in 2002 in 12 centers in Northern, Center and Southern Italy, different in size, climate, latitude and level of urbanization. Standardized questionnaires filled in by parents were used to collect information on health outcomes and exposure to traffic among 33,632 6-7 and 13-14 years old children and adolescents. Three questions on traffic exposure were asked: the traffic in the zone of residence, the frequency of truck and of car traffic in the street of residence. The presence of a possible response bias for the self-reported traffic was evaluated using external validation ( comparison with measurements of traffic flow in the city of Turin) and internal validations ( matching by census block, in the cities of Turin, Milan and Rome). Results: Overall traffic density was weakly associated with asthma symptoms but there was a stronger association with cough or phlegm ( high traffic density OR = 1.24; 95% CI: 1.04, 1.49). Car and truck traffic were independently associated with cough or phlegm. The results of the external validation did not support the existence of a reporting bias for the observed associations, for all the self-reported traffic indicators examined. The internal validations showed that the observed association between traffic density in the zone of residence and respiratory symptoms did not appear to be explained by an over reporting of traffic by parents of symptomatic subjects. Conclusion: Children living in zones with intense traffic are at higher risk for respiratory effects. Since population characteristics are specific, the results of validation of studies on self-reported traffic exposure can not be generalized.

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