DSpace Repository :: Browsing by Author "Simbauni, Jemimah A."

Browsing by Author "Simbauni, Jemimah A."

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Drug Recovery: Effect of Astemizole - Methylene Blue Combination Therapy against Plasmodium Strains in vitro
(South Asian Journal of Parasitology, 2020) Nyirongo, Joyce; Kamau, Lucy; Simbauni, Jemimah A.; Mwangi, Victor; Kagasi, Esther; Onditi, Faith; Ozwara, Hastings
Plasmodium species are protozoa from the Apicomplexa phylum which cause malaria. In the tropics and sub-tropics, approximately 3.3 billion people are threatened by this disease. Artemisinin Combination Therapy, has been reported to have a possible emergence of resistance. Therefore, there is an urgent need for new drug formulations. Drug repurposing offers an appealing alternative to de novo drug development. Although astemizole and methylene blue have been reported to have anti-malarial properties, their efficacy when used in combination has not been studied. Five concentrations ranging from 7.81 µg/ml to 125 µg/ml were combined in various ratios and assessed against two Plasmodium strains in vitro. Parasite load (per µl of blood) was determined by microscopy. The results were represented as mean ± standard error. ANOVA analysis was used to determine differences in the treatment groups at p<0.05. Antiplasmodial activity was observed in all drugs that were cultured with P. falciparum chloroquine sensitive (3D7) and chloroquine resistant (W2) strains. Strain dependent differences were observed in the efficacy scores of the tested drugs. Astemizole-methylene blue combinations of ratios 1:1, 3:1 and 1:3 interacted antagonistically. The least antagonistic interactions were 3:1 and 1:3 ratios at 31.25 µg/ml against the Plasmodium strains (FIC of 2.2 and 2.6 respectively). Astemizole antagonized methylene blue in the combinations. This study provided information on the importance of astemizole-methylene blue combination therapy against malaria and emphasized on the relevance of drug repurposing in malaria. This study shows that the drugs work better as monotherapies and that combinations in these ratios have insignificant antiplasmodial activity.
Effect of habitat fragmentation on some aspects of reproduction among Praomys delectorum sub-populations in the Taita and Kyulu Hills, Kenya
(Darshan publishers, 2016) Gitonga, J.; Simbauni, Jemimah A.; Oguge, N.
In small mammals particularly rodents, selection generally favours the production of relatively many offsprings per litter. Intraspecific litter size variation requires individual mothers to establish an optimal litter size in terms of fitness consequences. Because mammalian reproduction is energetically very demanding, litter size decisions are influenced by the maternal condition and environmental factors. Environmental constraints associated with the availability and quality of food during pregnancy and lactation may limit the acceleration in energy expenditure that occurs during reproduction, which may in turn negatively affect reproductive success of small mammals. This study investigated the effect of habitat fragmentation on litter size of Praomys delectorum in three sub-populations of the Taita Hills and the Kyulu Hills population. The presence of foetuses and placental scars were used as litter size indicators. The histology of testes and ovaries, based on routine histological techniques was studied to ascertain the reproductive status of the animals. There was no significant difference in litter size ( F3,15 = 0.126 ns P =0.943) among the different sub-populations. Prominent nuclei of primary spermatocytes in the seminiferous tubules of both abdominal and scrotal testes were indicative of spermatogenesis though germ cells organization was clearer in scrotal testes. The ovary of female with plugged vagina lacked corpora lutea which were nonetheless observed in the ovary of females with perforate vagina though developing Graafian follicles were observed in both. Thus vaginal condition is a good indicator of reproductive status in this species.
Effects of soil- transmitted helminths and schistosoma species on nutritional status of children in Mwea Irrigation Scheme, Kenya
(Sciencedomain International, 2016-04) Njiru, J.M.; Muhoho, N.; Simbauni, Jemimah A.; Kabiru, Ephantus W.
Aim: Soil- transmitted helminths (STH) and schistosomiasis are a major public health problem in Kenya as well as in many other tropical countries. Intestinal parasite infections have been associated with malabsorption and nutrient loses that can lead to malnutrition. Malnutrition is considered one of the most prevalent conditions among children in rural population. The aim of this study was to investigate the effects of STH and S. mansoni parasite infections on nutritional status of school children in Mwea rice Irrigation Scheme. Study Design: The study was descriptive cross-sectional in design. Methodology: The study was carried out in selected schools within Mwea Irrigation Scheme. The sample size comprised 236 children at the baseline with 78 pupils from Kandongu, 89 from Kirogo and 69 from Nyangati primary schools. A sub-sample of 103 pupils was randomly selected from the sample population and used to assess the prevalence of anaemia. A sub-sample was necessary in this case due to economic and logistic problems. Results: Overall prevalence rate of geohelminths and Schistosoma infections was found to be 26%. There was a strong relationship between infection and malnutrition with the number of pupils infected and underweight being 59% compared to17.9% of non infected underweight. Helminth infections were also associated with anaemia, with 65.7% of anaemic cases suffering from various types of helminth infections. Conclusion: The study has indicated that intestinal helminth infections, including soil transmitted helminths and Schistosoma mansoni cause malnutrition and anaemia among the school children in Mwea Irrigation Scheme, having been associated with severe, moderate to mild malnutrition as well as anaemia. Keywords: Soil- transmitted helminthes; Schistosoma mansoni; malnutrition; prevalence of infection; irrigation.
Evidence of Regeneration of Testicular and Epididymal Tissue Structure and Function Following Withdrawal from Sub-chronic Khat Exposure: Studies in the Rabbit Animal Model
(Journal of Applied Life Sciences International, 2020) Nyongesa, Albert W.; Maluki, Esther M.; Simbauni, Jemimah A.
Khat, Catha edulis, use is rampant in Eastern Africa and Middle East countries with associated reports of reproductive function impairment in the body of the user. Reports on recovery post longterm khat exposure are obscure. The present study investigated evidence of restoration of testicular and epididymal structure and function during withdrawal from cytotoxic damage caused by subchronic exposure of khat extract. Twenty-eight male rabbits were divided into 7 groups of 4 rabbits each. Group I (control) was administered normal saline while groups II, III and IV were administered 1.0 g/kg, 10 g/kg and 20 g/kg body weight of khat extract, respectively, via oral gavage on alternate days of the week for 12 weeks. Blood samples from animals were collected for hormonal assays followed by euthanasia using 26.4 mg/kg body weight of Sagatal sodium intramuscularly for testicular and epididymal histology. Group V, VI and VII were administered 1.0 g/kg, 10 g/kg and 20 g/kg body weight of khat extract, respectively, orally on alternate days of the week for 12 weeks followed by 1-month withdrawal period, blood samples collected for hormone assays and animals sacrificed for testicular and epididymal histology. High khat dose, 20 g/kg body weight, at subchronic exposure caused degeneration in spermatogenic cells with accompanying decrease in plasma FSH and testosterone. Histological output of Sertoli cells, Leydig cells and epididymal epithelium appeared unaffected in treatment groups. Post withdrawal data showed apparent regeneration of seminiferous epithelium and restoration of plasma FSH and testosterone comparable to control. It appears khat extract preferentially affected germ cell spermatogonia and subsequent daughter cells while stem cell spermatogonia were unaffected and contributed to regeneration of germinal epithelium and endocrine function.
Habitat fragmentation and occurrence of intestinal parasites among the Praomysdelectorum sub-populations in Taita and Kyulu hills, Kenya
(2016) Gitonga, John; Simbauni, Jemimah A.; Oguge, Nicholas
Rodents, like other wild animals, are subject to a wide variety of parasitic infestation. Although wild animals are usually infected with several species of parasites, they seldom suffer massive deaths or epizootic. This is due to the normal dispersal and territorialism of most species. Despite the fact that most wild animals tolerate their parasite burdens fairly well, the animals will succumb when crowded and suffering from malnutrition. This study investigated the occurrence and the variety of intestinal parasites among the different sub-populations of Praomys delectorum in Taita and Kyulu Hills. Microscopic studies were conducted on the digesta of the animals. Threedifferent species of intestinal parasites were identified i.e. Hymenolepis sp, Trichostronglus sp and Trichuris sp. All the animal groups were found to have the ova and the adult Hymenolepis sp and only the Kyulu group had Trichuris species ova. The percentage infection varied between 25% and 63.16% across all the sub-populations. The Kyulu sub-population with the leastanthropogenic disturbance or a more stable ecosystem had the highest prevalence of parasites (63.16%). Of the Taita Hills sub-populations, Ngangao, with the least anthropogenic disturbance and lowest population of Praomysdelectorum, had the lowest prevalence of intestinal parasites at 25%. Density of rodent population, habitat type and degree of anthropogenic disturbance are factors that determine the occurrence and prevalence of intestinal parasites in the animal species under study
Human Footprint and Rainfall Shape Masai Giraffe’s Habitat Suitability and Connectivity in a Multiple-Use Landscape
(ECOSPHERE, 2024) Muthiuru, Amos C.; Crego, Ramiro D.; Simbauni, Jemimah A.; Muruthi, Philip M.; Waiguchu, Grace; Lala, Fredrick; Millington, James D. A.; Kairu, Eunice W.
Giraffe populations have declined by around 40% in the last three decades. Climate change, poaching, habitat loss, and increasing human pressures are confining giraffes to smaller and more isolated patches of habitats. Masai giraffes (Giraffa tippelskirchi) have been subjected to habitat loss and fragmentation, diseases, poaching, and unpredictable calamities such as wildfires and climate change. In this study, we aimed to identify (1) suitable Masai giraffe habitats within the transboundary landscape of Tsavo-Mkomazi in Southern Kenya and Northern Tanzania; and (2) key connecting corridors in a multiple-use landscape for conservation prioritization. We combined Masai giraffe presence data collected through a total aerial survey with moderate resolution satellite data to model habitat suitability at 250 m resolution using species distribution models (SDMs) implemented in Google Earth Engine (GEE). Model accuracy was assessed using area under precision recall curve (AUC-PR). We then used the habitat suitability index as a resistance surface to model functional connectivity using Circuitscape theory and cost-weighted distance pairwise methods. Human habitat modification, rainfall, and elevation were the main model predictors of Masai giraffe habitat and corridors. On average, our 10-fold model fitting attained a good predictive performance with an average AUC-PR = 0.80 (SD = 0.01, range = 0.79–0.83). The model predicted an area of 15,002 km2 as potential suitable Masai giraffe habitat with over 17% outside protected areas within the landscape. Although Tsavo West National Park formed a key habitat and a key connecting corridor, nonprotected community ranches connecting Tsavo West and Tsavo East National Parks are equally important in maintaining landscape connectivity joining more than two Masai giraffe core areas with low resistance and high permeability. To maintain critical Masai giraffe’s habitats and landscape functional connectivity, especially in multiple-use landscapes, conservation-compatible land use practices, capacity building, and land use planning should be considered at the outset of any new infrastructure development and land use changes. This modeling shows the potential of utilizing remotely sensed information and ground surveys to guide the management of habitats and their connecting corridors across important African landscapes, complementing existing efforts to identify, conserve, and protect wildlife habitats and their linkage zones
Physical, chemical and biological characteristics in habitats of high and low presence of anopheline larvae in western Kenya highlands.
(PLoS One., 2012) Ndenga, B. A.; Simbauni, Jemimah A.; Mbugi, J. P.; Githeko, A. K.
BACKGROUND: Characteristics of aquatic habitats determine whether mosquitoes will oviposit, hatch, develop, pupate and successfully emerge into adults or not, thus influencing which mosquito species will occupy a habitat. This study determined whether physiochemical and biological characteristics differ between habitats with high and low presence of anopheline larvae. METHODS: Physical, chemical and biological characteristics were evaluated in selected habitats twice per month within three highland valleys in western Kenya. Aquatic macro-organisms were sampled using a sweep-net. Colorimetric methods were used to determine levels of iron, phosphate, nitrate, ammonium and nitrite in water samples. Generalized Estimating Equations (GEE) was used to compare parameters between the two categories of anopheline presence. RESULTS: Habitats with high anopheline presence had greater abundance of mosquito aquatic stages and tadpoles and two times more levels of nitrate in water, whereas habitats with low anopheline presence had wider biofilm cover and higher levels of iron in water. CONCLUSION: Habitats of high and low presence of anopheline larvae, which differed in a number of physical, chemical and biological characteristics, were identified in valleys within western Kenya highlands. Differences in habitat characteristics are critical in determining the number of anopheline larvae that will fully develop and emerge into adults.
Productivity of malaria vectors from different habitat types in the western Kenya highlands.
(PLoS One., 2011-04) Ndenga, B. A.; Simbauni, Jemimah A.; Mbugi, J. P.; Githeko, A. K.; Fillinger, U.
BACKGROUND: Mosquito Larval Source Management (LSM) could be a valuable additional tool for integrated malaria vector control especially in areas with focal transmission like the highlands of western Kenya if it were not for the need to target all potential habitats at frequent intervals. The ability to determine the productivity of malaria vectors from identified habitats might be used to target LSM only at productive ones. METHODS: Each aquatic habitat within three highland sites in western Kenya was classified as natural swamp, cultivated swamp, river fringe, puddle, open drain or burrow pit. Three habitats of each type were selected in each site in order to study the weekly productivity of adult malaria vectors from February to May 2009 using a sweep-net and their habitat characteristics recorded. RESULTS: All surveyed habitat types produced adult malaria vectors. Mean adult productivity of Anopheles gambiae sensu lato in puddles (1.8/m(2)) was 11-900 times higher than in the other habitat types. However, puddles were the most unstable habitats having water at 43% of all sampling occasions and accounted for 5% of all habitats mapped in the study areas whereas open drains accounted for 72%. Densities of anopheline late instars larvae significantly increased with the presence of a biofilm but decreased with increasing surface area or when water was flowing. Taking stability and frequency of the habitat into account, puddles were still the most productive habitat types for malaria vectors but closely followed by open drains. CONCLUSION: Even though productivity of An. gambiae s.l. was greatest in small and unstable habitats, estimation of their overall productivity in an area needs to consider the more stable habitats over time and their surface extension. Therefore, targeting only the highly productive habitats is unlikely to provide sufficient reduction in malaria vector densities.
A Screening Experiment on a Diabetes Mellitus Herbal Formulation
(Science Publishing Group, 2016) Njoroge, G.G.; Koske, J.A.; Simbauni, Jemimah A.
Screening experiments are usually performed on mixtures in order to determine the experimental variables that have significant influence on the targeted response. In this study, a screening experiment was carried out on a herbal formulation prescribed by a registered Kenyan herbalist to diabetes mellitus type II patients. The herbal formulation was composed of the following six herbs: Utica dioica, Moringaoleifera, Cinnamomum verum, Azadirachta indica, Momordica charantia and Gymnema sylvestre. The targeted response was the change that had occurred in blood glucose level 2 hours after the herbal drug treatment had been administered to alloxan induced diabetic albino wistar rats. An axial mixture design with replicated centre points was adopted and a first degree mixture model fitted to the data. The axial mixture design was constructed using Design Expert® software with randomly distributed 23 design points positioned on the component axes. The analysis of the data was carried out using the R statistical software environment. The results showed that Cinnamomum verum and Azadirachta indica caused the highest change individually on the blood glucose level among the six herbs. The complete mixture of the six herbs registered the lowest reduction in the blood glucose level. We recommend that the two herbs, Cinnamomum verum and Azadirachta indica, be tested farther to find out the most optimal conditions for their extraction in terms of temperature and time so as to produce a maximum reduction on the blood glucose level. In addition, we recommend that this study be extended to higher animals to establish whether the same patterns would be observed and also obtain the appropriate dosage levels.
Studies on some reproductive physiological aspects of the Kenyan fruit bat, eldolon helvum (KERR, 1792) (Megachiroptera)
(2012-06-05) Simbauni, Jemimah A.
Cytochemical procedures have been used to study the anterior pituitary gland (adenohypophysis) of the Kenyan fruit bat Eidolon helvum (Kerr, 1792) during various reproductive phases, which comprise preovulatory, ovulatory, delayed implantation and pregnancy phases. The main purpose for these histophysiological investigations is to identify adenohypophyseal celltypes whose hormonal secretions directly or indirectlyinduce delayed implantation in the fruit bat under study. In a light-microscope study based on the size, shape and tinctorial affinities, six cell types have been identified in the adenohypophysis. There are three types of basophils notable for the presence of acid muccopolysaccharides in their cytoplasm, two types of acidophils notable for the presence of phospholipids and lipoproteins in their cytoplasm and the chromophobes which do not contain any stainable garnules. Periodic Acid Schiff's (PAS) reaction for carbohydrates has been used to distinguish between he basophils nad acidophils. All the PAS positive cells are referred to as basophils. PAS in combination with other dyes for example Alcian Blue have enabled further differentiation of basophils into three types, namely, type I basophil, type II basophil and type III basophil. Two types of acidophil cells in which carbohydrates are absent w ere identified namely: type I and II by their negative reaction with Period Acid Schiff's technique for mucoid substances and positive reaction with either Orange G or azocarmine B ('Azan Stain). The precise differentiation of the two acidophils is achieved by employing Brooke's (1964) method for lipids. The sixth celltype which lacks stainable granules was identified as the Chromophobe. The basophils type I, II and III were identified as Thyroid Stimulating Hormone (TSH), Follicle Stimulating Hormone (FSH), and Leutinizing Hormone (LH) cells respectivelyo n the basis of their tinctorial affinities. The adicophil cell type I and II were identified as somatotrophs (STH cells) and prolactin cells (PRL) respectively. Further the hormonal assays of progesterone, LH and prolactin at various reproductive phases was carried out by Radio-Immuno Assays (RIA) and Enzyme - Linked Immuno Assays (ELISA). The level of progesterone hormone was highest during pregnancy 56.45 ng/ml and lowest at delayed implantation period 1.626 ng/ml. The level of prolactin hormone was highest (7.67 ng/ml) during the period of delayed implantation and lowest 0.89 ng/ml at pre-ovulatory period. The level of LH was lowest during delayed implantation period (2.08 ng/ml). Electron microscopic (EM) studies on these cell types identified various cell organelles including nuclei, endoplasmic reticulum, mitochondria, ncleoli, Golgi apparatus, secretory vesicles etc. Six morphologically distinguishable cell types in the anterior pituitary gland of the female bat were identified. These cells were designated as type I-VI (TSH, FSH, LH, STH, PRL/LTH and chromophobes) on the basis of their secretory granules and other cytoplasmic organelles. When the female bats enter delayed implantation stage there is a remarkable rise in the number of granular prolactin cells (Brooke's method) with a concomitant depletion in the FSH and LH cells. These alterations in the adenohypophyseal cells are acoompanied by weight changes in the ovary and uterus. These observations suggest the involvement of prolactin in inducing delayed implantation. Hyperprolactinaemia suppresses gonadal function, probably by a short-loop inhibition of LH/FSH release. The mean values of the numbers of various types of cells observed and hormonal assays of LH, progesterone and prolaction during the different reproductive stages were calculated and the relationship between them determined using the chi-squared in a large table and regression techniques (Parker, 1979; Gomez and Gomez, 1984). Consequently, for the mean (In) cell and the mean (In) hormonal values, the standard errors were calculated. In E. helvum implantation occurs roughly 90 days after conception. During delayed implantation period the conceptus develops only as far as the bilaminar blastocyst stage. During this period, conspicuous changes occur in the endometrium, lining epithelium, and glands of the uterus. The reason for such a long delayed implantation period (±90 days from the zygote until implantation during the bilaminar blastocyst stage) can only be to ensure that the juveniles will leave the maternity at a time which coincides with the higher reainfall peaks when availability of fruits is at a maximum (Mutere, 1967). Moreover, since implantation is considered a promising target for contraception, the present study might help in future to define targets of attack for the development of new contraceptive agents for human use and welfare, taking into consideration the role of prolactin in both male and female subjects.

Browsing by Author "Simbauni, Jemimah A."

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