Papers by Prof. Irene Ayi
ChemInform, 2010
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Journal of Fluorine Chemistry, 1992
We have previously established a series of equations which may be applied to 2,5dioxopiperazines ... more We have previously established a series of equations which may be applied to 2,5dioxopiperazines (DOP) with either unfluorinated side-chains (c[Xaa-Yaa]) or a fluorine atom on the p position on one of the lateral chains (c[X(F)aa-Yaa]) [l]. From these equations and 'H and "F NMR spectra, it is possible, on the one hand, to determine the conformation of the DOP ring, and, on the other hand, to calculate the populations of rotamers of the fluorinated or non-fluorinated lateral chains. Comparison shows that if the conformations of the DOP rings are identical (other than one case), the conformation of the lateral chains is strongly modified by the presence of the fluorine atom which always lies above the DOP ring. R&urn6 Nous avons etabli precedemment une serie d'equations qui, par application a des 2,5dioxopiperazines (DOP), c[Xaa-Yaa], dont les chaines laterales sont non fluorees ou qui possedent un atome de fluor en position /3 sur l'une des chaines lat.&ales c[X(F)aa-Yaa], nous permettent a partir de mesures en RMN 'H et "F de determiner la conformation du cycle DOP dans chacun des cas envisages et de calculer les populations de rotameres des chames laterales que celIes-ci soit fluorees ou non. La comparaison montre que si les conformations des cycles DOP sont identiques (sauf dans un cas), la conformation des chaines laterales est profondement modifiee par la presence de l'atome de fluor. Celui-ci se situe toyjours au-dessus du cycle DOP. Conformation en solution des 2,hlioxopiphrazines non fluorkes Nous avons rassembl6 dans les Tableaux 1-6 les mesures de RMN que nous avons r&h&es ou qui sont tir6es de la littkature, ainsi que les rksultats des calculs, effectuk 2 park-des kquations dtk-ites pr&+demment [ 1 I. Les *Parties I et II, ref. 1.
Journal of Fluorine Chemistry, 1991
Starting from two types of monofluorinated dipeptides diketopiperazines c[Xaa-Yaa] , in which Xaa... more Starting from two types of monofluorinated dipeptides diketopiperazines c[Xaa-Yaa] , in which Xaa was a B-monofluorinated a-aminoacid residue and Yaa a natural cxaminoacid residue, were synthesized. INTRODUCTION Les 2,5 dioxopiperazines (ou DOP) sont largement repandues dans la nature [ 1.21. On en trouve dans les lichens, les levures, les champignons, dans les fluides biologiques. Ce sont des produits de degradation de protcines ou de polypeptides. Les DOP sont aussi des produits secondaires form& au tours de la synthtse de nombreux peptides [3,4] et au tours de leur decomposition [5]. Les 25dioxopiperazines naturelles ou synthetiques posstdent de remarquables propriCtts biologiques et pharmacologiques. Certains dipeptides cycliques, ou des substances en derivant, sont interessants d'un point de vue medical en tant qu'inhibiteurs d'enzymes, agents antitumoraux ou antibiotiques [ 1,6]. Cette famille de composks est connue depuis le dbbut du sibcle [7]. Mais, ce nest qu'A partir de 1970, aprks la mise en Cvidence des propriCtCs mtdicales intkressantes de ce type de substance, qu'un grand nombre de DOP ont 6tC synthttisCes.
Journal of Fluorine Chemistry, 1992
Peptides incorporating one or more /34luorinated amino acids in their structure are of great inte... more Peptides incorporating one or more /34luorinated amino acids in their structure are of great interest because the distribution of electronic charges on the peptide bond near the fluorine atom is altered. This property could modify enzymatic reactions, e.g. hydrolysis. Moreover, the introduction of fluorine into a peptide may modify its secondary and tertiary structure, leading to a different affinity for the enzyme for which the unfluorinated variety is the substrate. Since it is diihcult to analyse the influence of the fluorine atom on the structure of a linear peptide in solution by NMR spectroscopy, a possible approach could be to study derivatives such as cyclodipeptides. In this work, we discuss equations for studying the most stable conformations of various dioxopiperazine (DOP) rings and side chains with a view to evaluating the influence of the fluorine atom.
Microbial Risk Analysis, Aug 1, 2017
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Acta Tropica, Nov 1, 2019
Aim: Gastrointestinal parasitism is a serious constraint affecting goat production in the Philipp... more Aim: Gastrointestinal parasitism is a serious constraint affecting goat production in the Philippines. This study aimed to determine the prevalence and associated risk factors of gastrointestinal nematode infection in goat-populated barangays of Baybay City, Leyte. Materials and Methods: A total of 81 households or farms were interviewed, and 450 goats were sampled for fecalysis. Fecal egg count along with egg morphological identification and coproculture for third stage larvae identification were conducted. Descriptive statistics and logistic regression analyses were carried out to determine the farm-and animal-level prevalence and risk factors. Results: Fecalysis revealed the presence of strongyle and Trichuris spp. with a farm-level prevalence of 100% and 4.94%, respectively; and animal-level prevalence of 96.22% and 4.44%, respectively. The identified strongyle genera per barangay were Haemonchus spp. (34.79%), Trichostrongylus spp. (33.29%), Oesophagostomum spp. (24.21%), Cooperia spp. (6.93%), and Chabertia spp. (0.79%). Goats older than 12 months were four times more likely to present high strongyle burden when compared to goats <6 months. With each month increase in goat's age, the odds of acquiring strongyle infection also increased by 1.07 times. Animals kept in goat house with cemented flooring have lower odds of acquiring strongyle (odds ratio=0.12). Goats raised for leisure purposes and fed with carabao grass (Paspalum conjugatum) were 8.12 and 5.52 times more likely to acquire Trichuris, respectively. Conclusion: Most of the backyard goat raisers in Baybay City, Leyte, do not practice sound helminth control measures as shown by the high prevalence of gastrointestinal nematodes. The most relevant risk factors for gastrointestinal nematode infection were the age of the goat, type of goat house's flooring, purpose of raising goats, and feeding practices.
Infection, Genetics and Evolution, Nov 1, 2017
Cryptosporidium and Giardia are major causes of diarrhoea in developing countries including Ghana... more Cryptosporidium and Giardia are major causes of diarrhoea in developing countries including Ghana, however, nothing is known about the species and subtypes of Cryptosporidium and Giardia in farmers and their ruminant livestock in this country. A total of 925 faecal samples from humans (n = 95), cattle (n = 328), sheep (n = 217) and goats (n = 285), were screened for Cryptosporidium and Giardia by quantitative PCR (qPCR) at the 18S rRNA and glutamate dehydrogenase (gdh) loci respectively. Cryptosporidium positives were typed by sequence analysis of 18S and 60 kDa glycoprotein (gp60) loci amplicons. Giardia positives were typed at the triose phosphate isomerase (tpi), beta-giardin (bg) and gdh loci. The prevalence of Cryptosporidium and Giardia by qPCR was 8.4% and 10.5% in humans, 26.5% and 8.5% in cattle, 34.1% and 12.9% in sheep, and 33.3% and 12.3% in goat faecal samples, respectively. G. duodenalis assemblages A and B were detected in humans and assemblage E was detected in livestock. Cryptosporidium parvum was the only species identified in humans; C. andersoni, C. bovis, C. ryanae and C. ubiquitum were identified in cattle; C. xiaoi, C. ubiquitum and C. bovis in sheep; and C. xiaoi, C. baileyi and C. parvum in goats. This is the first molecular study of Cryptosporidium and Giardia in livestock in Ghana. The identification of zoonotic species and the identification of C. parvum subtype IIcA5G3q in livestock, which has previously been identified in children in Ghana, suggests potential zoonotic transmission. Further studies on larger numbers of human and animal samples, and on younger livestock are required to better understand the epidemiology and transmission of Cryptosporidium and Giardia in Ghana.
Background: School children have been increasingly recognized as health messengers for malaria co... more Background: School children have been increasingly recognized as health messengers for malaria control. However, little evidence is available. The objective of this study was to determine the impact of school-based malaria education intervention on school children and community adults. Methods: This study was conducted in the Dangme-East district of the Greater Accra Region, Ghana, between 2007 and 2008. Trained schoolteachers designed participatory health education activities and led school children to disseminate messages related to malaria control to their communities. Three schools and their respective communities were chosen for the study and assigned to an intervention group (one school) and a control group (two schools). Questionnaire-based interviews and parasitological surveys were conducted before and after the intervention, with the intervention group (105 children, 250 community adults) and the control group (81 children, 133 community adults). Chi-square and Fisher's Exact tests were used to analyse differences in knowledge, practices, and parasite prevalence between pre- and post-intervention. Results: After the intervention, the misperception that malaria has multiple causes was significantly improved, both among children and community adults. Moreover, the community adults who treated a bed net with insecticide in the past six months, increased from 21.5% to 50.0% (p < 0.001). Parasite prevalence in school children decreased from 30.9% to 10.3% (p = 0.003). These positive changes were observed only in the intervention group. Conclusions: This study suggests that the participatory health education intervention contributed to the decreased malaria prevalence among children. It had a positive impact not only on school children, but also on community adults, through the improvement of knowledge and practices. This strategy can be applied as a complementary approach to existing malaria control strategies in West African countries where school health management systems have been strengthened. Background Ghana is located in sub-Saharan Africa, where an estimated 90% of the world's malaria-attributable deaths occur. In Ghana, malaria accounts for more than 44% of reported outpatient visits and an estimated 22% of deaths in children under the age of five. Reported malaria cases represent only a small proportion of the actual number of episodes, as the majority of people with symptomatic
AFRICAN JOURNAL OF FOOD, AGRICULTURE, NUTRITION AND DEVELOPMENT, 2017
Vitamin A deficiency (VAD), anaemia, and parasitic infections are among the major nutritional and... more Vitamin A deficiency (VAD), anaemia, and parasitic infections are among the major nutritional and health problems confronting Ghanaian school children. This study assessed the impact of red palm oil bean-stew consumption on serum retinol and haemoglobin concentrations of Ghanaian school children in a malaria-endemic setting. The design was a pre-post nutrition intervention study. It involved 142 6-12 year-old children. Participants were selected by simple random sampling. After baseline sample and data collection, the participants consumed red palm oil bean-stew with gari (made from fermented, grated cassava flour), three times a week for a period of six months. Final biological samples and data were collected as at baseline. Dietary data were collected using Food Frequency Questionnaires and the 24-hour recall procedure. Serum retinol was measured with High Performance Liquid Chromatography and haemoglobin by Haemocue Haemoglobinometer. Malaria parasitaemia and hookworms were examined by microscopy from blood films and stool samples using the Giemsastaining and Kato-Katz techniques, respectively. Data were analysed with Statistical Package for Social Sciences version-23. Mean values for outcome variables were compared between baseline and final using paired t-tests. Results indicated that majority of the participants (82.4%) consumed cereals. Many of them also (98.6%) never consumed dairy or dairy products. Mean serum retinol concentration was 12.1 ± 6.6µg/dl during baseline and 16.2 ± 6.4µg/dl at final, the difference significant at p<0.05. The mean haemoglobin concentration at baseline was 119.4 ± 10.6 g/l and 126.0 ± 9.34g/l at final, with a significant difference at p<0.05. The prevalence of VAD defined as serum retinol concentration <20µg/dl was 76.2% at the end of the study being significantly different from that at baseline (93.6%), p<0.05. Prevalence of anaemia was 30.3% and 11.3% at baseline and final, respectively with a significant difference at p<0.05. Malaria parasitaemia was prevalent: 67.6 % at baseline and 62.7% at the end of the study. Only one participant (0.01%) was found with hookworm infestation. For participants with VAD, 48.3% and 36.2% improved to moderate and normal vitamin A status, respectively at the end of the study. The prevalence of anaemia among VAD participants was 36.2 % at baseline and 12.1 % at final. In conclusion, red palm oil beanstew consumption increased the haemoglobin concentration and minimized prevalence of anaemia among the study participants. It also increased serum retinol concentrations and minimized the prevalence of vitamin A deficiency (especially severe vitamin A deficiency) among the study participants.
Tetrahedron Letters, Dec 1, 2015
The strong anti-trypanosomal active compound, molucidin, contains a spirolactone tetracyclic irid... more The strong anti-trypanosomal active compound, molucidin, contains a spirolactone tetracyclic iridoid skeleton and is isolated from Morinda lucida as an enantiomer of oruwacin, which is isolated from the same plant. To confirm the absolute configuration of molucidin, we prepared single crystals of molucidin for X-ray analysis. The absolute configuration of the afforded single crystal was determined by X-ray crystallography using a Cu radiation source. The X-ray diffraction data were collected at 93 K in the 2θ range 7.468°-134.99° and analyzed using the SHELXL-2014 program. The corresponding chiral quaternary carbon atoms in molucidin were unambiguously determined as 1R, 5S, 8S, 9S, and 10S. Notably, both enantiomers of a single moleucle, molucidin and oruwacin, with a rigid structure have been isolated from the same plant species. The biosynthetic pathway for formation of molucidin is also discussed on the basis of the absolute configuration. Our results for the first time support for structural elucidation of tetracyclic iridoids using X-ray analysis.
Neglected tropical diseases, 2016
The human burden of soil-transmitted helminthiasis is highest in sub-Saharan Africa (SSA) than in... more The human burden of soil-transmitted helminthiasis is highest in sub-Saharan Africa (SSA) than in other parts of the planet. The major parasites that contribute to the global burden, Ascaris, Trichuris, hookworm, schistosomes, and Strongyloides, and even less known ones such as Oesophagostomum bifurcum and Ternidens deminutus (a.k.a. “false hookworm”) all occur in SSA. In this chapter, the symptoms and consequences of infection by these parasites including retarded growth, reduced work capacity, poor school performance, adverse cognitive development, and nutritional and reproductive health problems are described for each parasite. The most at-risk groups for the diseases they cause are also specified. Why then is SSA carrying the highest burden? The answer is the diseases’ association with ignorance or lack of awareness, poor personal and environmental hygiene, poverty, impoverished health services, and economic development. These factors are common to these helminths’ infections and also explain to a large degree the skewed high prevalence of the diseases in rural African communities. The parasites all share similar basics of the life cycle except for Strongyloides stercoralis which in addition is also capable of autoinfection (i.e., multiplication) in human and of existing as free living and productive adults in the environment, attributes which make it difficult to control. Treatment and challenges with mass drug administration (MDA) with antihelminthics and the urgent need for more sensitive diagnostic tools than the existing ones for scenarios of low-intensity infections and the likelihood of resistance developing with the MDA are highlighted. There are opportunities arising from recent technological advancements such as the availability of genome data of 22 helminth species to be exploited for novel drugs and vaccine design and of IT tools, remote sensing data, and global resource platforms for disease mapping, ecology and epidemiology studies, operational research, and implementation of control programs. What it entailed in conducting a successful and sustainable STH control in a hitherto deprived community in Ghana is presented as a case study.
Parasitology International, Aug 1, 1998
Pruductiun of anti-rchiiosomal monoclonal antibodks (MAbs) was car&d out to be employed in serodi... more Pruductiun of anti-rchiiosomal monoclonal antibodks (MAbs) was car&d out to be employed in serodirgnosir of active schiiosomiuis. MAbs were r&d against S munsoni soluble egg antigens (SEA), S munson1 secretory excretory products (SEP) and S haemutobium SEA by fusion of spknocytes of
Research and Reports in Tropical Medicine, 2015
Background: Recent studies have shown the urine filtration and Kato-Katz techniques to significan... more Background: Recent studies have shown the urine filtration and Kato-Katz techniques to significantly underestimate infection intensity in Schistosoma haematobium and Schistosoma mansoni infections, respectively. Infection intensity determination by these methods improves only with increasing number of samples collected per participant. This implies tedious and lengthy periods of sample processing and analysis by microscopy examination, hence the increased chances of experimental errors. This study sought to determine the relationship between levels of eosinophil cationic protein (ECP) and infection intensity by egg count both in S. haematobium and S. mansoni single and coinfections. Methods: This was a cross-sectional study carried out in Pakro, a periurban community in Ghana, involving a total of 308 participants. Each provided urine and stool samples, which were processed using the filtration and Kato-Katz techniques, respectively. Processed samples were examined by microscopy. Aliquots of urine from 73 participants were analyzed for levels of ECP using an ECP enzyme-linked immunosorbent assay kit. Results: Of the 308 urine samples examined, 59 (19.15%) were positive for S. haematobium. Significant association was observed between sex and S. haematobium infection intensity by egg count (P,0.05) as well as between age and infection intensity (P,0.001). Mean ECP levels were higher in S. haematobium-positive samples than in S. haematobium-negative samples (P,0.001). There was also positive correlation between ECP and infection intensity (Spearman's r=0.73, P,0.001). Conclusion: This study showed that ECP levels are positively associated with infection intensity by egg count in Schistosomiasis infections, even after multivariate adjustment.
PLOS ONE, Oct 2, 2020
Resource-deprived coastal peri-urban settlements in Southern Ghana are characterized by indiscrim... more Resource-deprived coastal peri-urban settlements in Southern Ghana are characterized by indiscriminate solid waste disposal and open defecation practices. Persons engaged in waste handling in such communities perform their activities with little or no personal protective equipment. They are thus confronted with the risk of faecal pollution of the hands and other bodily parts. A mixed method approach was used to investigate 280 waste handlers performing different activities to estimate recent faecal pollution of their hands and to observe the utilization of personal protective equipment and sanitation/hygiene facilities during work. The log concentration of E. coli on hands of waste handlers after work (8.60 ± 4.20 CFU/hand, mean ± standard deviation) was significantly higher compared with the E. coli log concentration before work (2.95 ± 1.89 CFU/hand, mean ± standard deviation) (p<0.001). The odds of faecal pollution was significantly higher (aOR 4.2; 95% CI: 1.9-9.1) for workers aged 35 years and above compared with those less than 35 years; and for workers at public toilet facilities (aOR 3.0; 95% CI: 1.0-8.4) compared with those who worked for private waste handling companies. Female workers were, however, 60% less likely (aOR 0.4; 95% CI: 0.2-0.8) to experience faecal pollution of their hands compared with males. The workers had limited access to water and sanitation and hygiene facilities, and about one-fifth (n = 59; 21.1%) did not use personal protective equipment during work. Waste handlers should be provided and instructed in proper use of personal protective equipment, have access to sanitation facilities and adopt improved hygiene behaviour to avoid the risk of faecal pollution and associated disease risk.
Maternal and Child Nutrition, Jul 25, 2018
Understanding contextual risk factors for haemoglobin (Hb) status and anaemia of rural school-age... more Understanding contextual risk factors for haemoglobin (Hb) status and anaemia of rural school-aged children (SAC) and adolescents is critical in developing appropriate interventions to prevent anaemia. We analysed secondary data from the baseline of an impact evaluation of the Ghana School Feeding Programme to determine the severity of anaemia and contextual factors associated with anaemia and Hb status among rural SAC (6-9 years; n = 323) and adolescents (10-17 years; n = 319) in Ghana. We used regression models with variable selection based on backward elimination in our analyses. The mean Hb was 113.8 ± 13.1 g/L, and the overall prevalence of anaemia was 52.3%, being 55.1% and 49.5% among SAC and adolescents, respectively. We identified child's age (β = 2.21, P < 0.001); farm diversity score (β = 0.59,
Food and Nutrition Bulletin, Sep 1, 2015
Background: Nutritional anemia is a public health problem among Ghanaian schoolchildren. There is... more Background: Nutritional anemia is a public health problem among Ghanaian schoolchildren. There is need to employ dietary modification strategies to solve this problem through school and household feeding programs. Objective: To evaluate the effectiveness of cowpea-based food containing fish meal served with vitamin C-rich drink to improve iron stores and hemoglobin concentrations in Ghanaian schoolchildren. Methods: The study involved cross-sectional baseline and nutrition intervention phases. There were 150 participants of age 6 to 12 years. They were randomly assigned to 3 groups, fish meal-vitamin C (n ¼ 50), vitamin C (n ¼ 50), and control (n ¼ 50), and given different cowpea-based diets for a 6-month period. Height and weight measurements were done according to the standard procedures, dietary data were obtained by 24-hour recall and food frequency questionnaire, hemoglobin concentrations were determined by Hemocue Hemoglobinometer, and serum ferritin and complementreactive protein (CRP) were determined by enzyme-linked immunosorbent assay. Participants' blood
Trials, Jan 20, 2016
Background: 'Home-grown' school feeding programmes are complex interventions with the potential t... more Background: 'Home-grown' school feeding programmes are complex interventions with the potential to link the increased demand for school feeding goods and services to community-based stakeholders, including smallholder farmers and women's groups. There is limited rigorous evidence, however, that this is the case in practice. This evaluation will examine explicitly, and from a holistic perspective, the simultaneous impact of a national school meals programme on micronutrient status, alongside outcomes in nutrition, education and agriculture domains. The 3-year study involves a cluster-randomised control trial designed around the scale-up of the national school feeding programme, including 116 primary schools in 58 districts in Ghana. The randomly assigned interventions are: 1) a school feeding programme group, including schools and communities where the standard government programme is implemented; 2) 'home-grown' school feeding, including schools and communities where the standard programme is implemented alongside an innovative pilot project aimed at enhancing nutrition and agriculture; and 3) a control group, including schools and households from communities where the intervention will be delayed by at least 3 years, preferably without informing schools and households. Primary outcomes include child health and nutritional status, school participation and learning, and smallholder farmer income. Intermediate outcomes along the agriculture and nutrition pathways will also be measured. The evaluation will follow a mixedmethod approach, including child-, household-, school-and community-level surveys as well as focus group discussions with project stakeholders. The baseline survey was completed in August 2013 and the endline survey is planned for November 2015. Results: The tests of balance show significant differences in the means of a number of outcome and control variables across the intervention groups. Important differences across groups include marketed surplus, livestock income, per capita food consumption and intake, school attendance, and anthropometric status in the 2-5 and 5-15 years age groups. In addition, approximately 19 % of children in the target age group received some form of free school meals at baseline.
Ghana Medical Journal, Jun 8, 2010
Objectives: To investigate Toxoplasma infection among pregnant women in relation to exposure to i... more Objectives: To investigate Toxoplasma infection among pregnant women in relation to exposure to infection risk, age and pregnancy-related risk factors. Design and Methods: This cross-sectional study involved 294 pregnant women attending antenatal clinic in Accra who consented to participate. Personal and Toxoplasma infection risk related data were obtained by questionnaire interviews. Venous blood was safely drawn from each participant and spun to obtain sera. Each of the 159 randomly selected serum samples was tested for specific anti-Toxoplasma (anti-T. gondii) antibodies IgG, IgA and IgM using a commercial ELISA kit (Calbiotech Inc., CA). ELISA results were correlated with exposure to possible infection risk factors as well as age and pregnancy-related risk factors. Results: The 159 women aged 15-40 years in their first, second and third trimesters, numbered 29, 70 and 60, respectively. An overall anti-T. gondii antibodies IgG, IgA and IgM seroprevalence of 92.5% (147/159) was recorded, with 4.1% (6/147) of them having anti-IgG only. The remaining 88.7% (141/159) had anti-Toxoplasma antibodies IgG, IgA and IgM in various combinations and consisted of 17.7% (25/141) in their first, 44.0% (62/141) in their second, and 38.3% (54/141) in their third, trimesters. Twelve women (7.6%) were seronegative for all 3 antibodies Conclusions: Seroprevalence was high among the women and exposure to contact with cats' faeces was found to be the major T. gondii infection risk factor. Age and pregnancy-related risk factors did not have association with T. gondii infection within the limitations of this study.
Journal of Scientific Research and Reports, Nov 10, 2021
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Papers by Prof. Irene Ayi