Bio

Dr. Atunga Nyachieo

Having  completed my PhD in Biomedical Sciences (Mechanisms of human diseases) in March 2010 from University of Leuven (KULeuven, Belgium), MSc (Molecular Biology, KULeuven, Belgium) and BSc (Biochemistry, JKUAT), I embarked on research and training. Currently, I am Lecturer but also a research fellow/scientist working on various projects aimed at not only contributing to research knowledge but also guiding national policy. I am also involved in training of various Masters and PhD students who are attached to the currently ongoing projects.

Dr. Atunga Nyachieo

Publications


Submitted

2013

Nyachieo, A, Kiraithe MM, Spiessens C, Chai DC, Kiulia NM, D'Hooghe TM, Mwenda JM.  2013.  Short-term effects of high-dose khat on sperm parameters and reproductive hormonal levels in olive baboons (Papio anubis)., 2013. Gynecologic and obstetric investigation. 75(2):109-14. Abstract

The biological effects of khat (Catha edulis) on reproduction and fertility are inadequately investigated and controversial, hence we determined the effects of oral administration of high-dose khat on sperm parameters and male hormonal levels in olive baboons. In this study, 6 male baboons received a high dose of khat (500 g/week) during 1 month. Electroejaculation for sperm studies (concentration, motility and chromatin integrity) and plasma collection for hormonal analysis (testosterone, prolactin and cortisol) were done weekly during 1 month before and 1 month during khat administration as well as 2 weeks after the last dose of khat administration. Administration of khat extract induced a significant reduction in sperm motility (p = 0.008), sperm count (p = 0.041), sperm chromatin integrity (p = 0.0003), testosterone levels (p = 0.035) and prolactin levels (p = 0.0115), but not in cortisol levels and sperm volume (p > 0.05). The results suggest that high-dose khat decreases sperm quality and testosterone and hence may contribute to male infertility.

Dancet, EAF, Brännström M, Brasky K, Chai D, Chan AWS, Conn PM, Else J, Falconer H, Fazleabas AT, Farah IO, Goddeeris BM, Golos TG, Hau J, Hearn JP, Kariuki TM, Kyama CM, Lebovic DI, Mwenda JM, Ndung'u J, Nyachieo A, Parker J, Slayden OD, Stouffer RL, Strauss JF, Taylor HS, Vanderpoel S, Westergaard JG, Zelinski M, D'Hooghe TM.  2013.  The role of scientists and clinicians in raising public support for animal research in reproductive biology and medicine., 2013 Feb. Biology of reproduction. 88(2):33.
Nyachieo, A, Spiessens C, Chai DC, Kiulia NM, Willemen D, Mwenda JM, Bourgain C, D'Hooghe TM.  2013.  Ovarian tissue cryopreservation by vitrification in olive baboons (papio anubis): a pilot study., 2013. Gynecologic and obstetric investigation. 75(3):157-62. Abstract

Ovarian tissue cryopreservation by vitrification is an attractive technique for fertility preservation in women. However, this technique has not been optimized. The aim of this study was to evaluate the baboon as a model for the preclinical study of ovarian tissue cryopreservation by vitrification and thawing.

2012

Nyachieo, A, Spiessens C, Chai DC, Kiulia NM, Mwenda JM, D'Hooghe TM.  2012.  Baboon spermatology: basic assessment and reproducibility in olive baboons (Papio anubis)., 2012 Oct. Journal of medical primatology. 41(5):297-303. Abstract

Development of a reproducible baboon in vitro fertilization (IVF) system require optimized and reproducible sperm parameters. The objective of this study was to document basic spermatology values and investigate the reproducibility of these variables in the same baboons 1 or 3 months later in a larger number of baboons.

2011

Nyachieo, A, Spiessens C, Chai DC, Debrock S, Mwenda JM, D'Hooghe TM.  2011.  Randomized comparison of different ovarian stimulation regimens for assisted reproductive technology in baboons (Papio anubis)., 2011 Mar 15. Fertility and sterility. 95(4):1354-9. Abstract

To compare different methods of ovarian stimulation (OS) for assisted reproductive technology in baboons.

Li, W, Kiulia NM, Mwenda JM, Nyachieo A, Taylor MB, Zhang X, Xiao L.  2011.  Cyclospora papionis, Cryptosporidium hominis, and human-pathogenic Enterocytozoon bieneusi in captive baboons in Kenya., 2011 Dec. Journal of clinical microbiology. 49(12):4326-9. Abstract

Cyclospora papionis, Cryptosporidium hominis, and Enterocytozoon bieneusi were detected in 42 (17.9%), 6 (2.6%), and 29 (12.3%) of 235 newly captured baboons in Kenya, respectively. Most C. hominis subtypes and E. bieneusi genotypes found have been detected in humans in the area, suggesting that cross-species transmission of cryptosporidiosis and microsporidiosis is possible.

2010

Nyachieo, A, Spiessens C, Chai DC, Kiulia NM, Mwenda JM, D'Hooghe TM.  2010.  Separate and combined effects of caffeine and dbcAMP on olive baboon (Papio anubis) sperm., 2010 Jun. Journal of medical primatology. 39(3):137-42. Abstract

Improvement of baboon sperm capacitation is necessary for achieving high in vitro fertilization (IVF) rates in baboons. In this study, we evaluated separate and combined effects of caffeine and dbcAMP on baboon sperm capacitation.

Kiulia, NM, Netshikweta R, Page NA, Van Zyl WB, Kiraithe MM, Nyachieo A, Mwenda JM, Taylor MB.  2010.  The detection of enteric viruses in selected urban and rural river water and sewage in Kenya, with special reference to rotaviruses., 2010 Sep. Journal of applied microbiology. 109(3):818-28. Abstract

To determine the occurrence of eight human enteric viruses in surface water and sewage samples from different geographical areas in Kenya.

Enskog, A, Johannesson L, Chai DC, Dahm-Kähler P, Marcickiewicz J, Nyachieo A, Mwenda JM, Brännström M.  2010.  Uterus transplantation in the baboon: methodology and long-term function after auto-transplantation., 2010 Aug. Human reproduction (Oxford, England). 25(8):1980-7. Abstract

Techniques for uterus transplantation (UTx) have been developed in rodent/domestic animals towards future clinical introduction of UTx to treat uterine factor infertility. The aim of this study was to extend the UTx research into a non-human primate species by developing surgical techniques for uterus retrieval and transplantation in the baboon.

2009

Nyachieo, A;, Spiessens C;, Mwenda JM;, Debrock S;, D’Hooghe TM.  2009.  Improving ovarian stimulation protocols for IVF in baboons: Lessons from humans and rhesus monkeys. Abstract

The aim of this review paper is to provide a scientific basis for the development of ovarian stimulation (OS) protocols for in vitro fertilization (IVF) in baboons. Firstly, the evidence available regarding OS for assisted reproduction in baboons is reviewed based on available published data, assessed by a Pub Med search of papers published between 1970 and 2008 using the following key words: baboon, assisted reproduction, IVF, embryo, oocyte. Secondly, we discuss how state-of-the-art or potentially new OS protocols used in humans and in rhesus monkeys may offer guidance for the development of standardized and reliable OS protocols for IVF in baboons. Based on this review and discussion, we conclude that more randomized trials are needed to improve standardization of OS protocols for IVF in baboons with respect to gonadotrophin type, dose, duration of stimulation, ultrasound monitoring, and time interval between ovulation trigger and oocyte retrieval.

Kiulia, NM, Nyaundi JK, Peenze I, Nyachieo A, Musoke RN, Steele AD.  2009.  Rotavirus infections among HIV-infected children in Nairobi, Kenya. Abstract

Human rotaviruses have emerged as a leading cause of acute diarrhea in children <5 years of age worldwide. Although there are previous reports relating to various aspects of rotaviruses, there is limited data on the involvement of rotavirus infection in HIV-infected children. We therefore evaluated the importance of rotavirus infections in HIV-related diarrhea in Kenyan children. Fecal samples were collected from a total of 207 children during the period February 1999 to June 2000 and screened for HRV antigen by enzyme-linked immunosorbent assay (ELISA). Positive samples were analyzed by VP6 subgroup specificity assay, by polyacrylamide gel electrophoresis (PAGE) and reverse transcriptase/polymerase chain reaction (RT-PCR). Fourteen percent (29/207) of the samples were positive. HIV-seropositive children with diarrhea were more likely than their counterparts without diarrhea to have rotaviruses [23.3% (10/43) versus 2.9% (2/70); p = 0.0001]. Rotavirus strain G3P[6] was predominant. These results indicate that rotavirus is an important viral etiological agent causing diarrhea in HIV-seropositive children

2008

D'Hooghe, TM, Nyachieo A, Chai DC, Kyama CM, Spiessens C, Mwenda JM.  2008.  Reproductive research in non-human primates at Institute of Primate Research in Nairobi, Kenya (WHO Collaborating Center): a platform for the development of clinical infertility services. Abstract

The Institute of Primate Research (IPR; www.ipr.or.ke) is a WHO collaborating center for research in reproductive biology, infectious diseases and ecology/conservation. It includes a fully equipped surgical complex, >5000 square feet of laboratory space, a quarantaine facility, library, conference room, administrative offices, etc. More than 500 primates can be housed at IPR, mainly baboons. Reproductive research at IPR is applied to endometriosis, assisted reproduction, prevention of heterosexual transmission of HIV and includes the investigation of immunocontraceptives and placental retroviruses. Reproductive research capacities of IPR include: videolaparoscopic surgical equipment, surgical experience, endometrial biopsies and uterine flushes, ovarian stimulation, laparoscopic oocyte aspiration, hormonal analyses in baboon blood and urine, sperm assessment, in vitro culture and reproductive immunological investigations. During the last years, simultaneously with the development of baboon IVF, there have been contacts with several Kenyan gynecologists at the level of KEMRI (Kenya Medical Research Institute), KOGS (Kenyan Obstetrical and Gynecological Society), Kenyatta National Hospital and Aga Khan Hospital in Nairobi to develop clinical infertility services including low-budget high-quality IVF in Nairobi. The logic behind this initiative is that the Kenyans trained in non-human primate embryology, and IVF would be natural partners to develop human IVF in Kenya.

2005

D’alessandro, U, Dujardin J-C, Laurent T, Overmeir CV, Nyachieo A.  2005.  Plasmodium falciparum genotyping by microsatellites as a method to distinguish between recrudescent and new infections. Abstractatunga_nyachieo.pdf

In vivo tests for susceptibility to antimalarial drugs require molecular methods to distinguish recrudescence from new infection. The most commonly used DNA markers (merozoite surface proteins [MSPs]) are under immune selective pressure, which might lead to misclassification. We evaluated immunologically neutral microsatellite markers in blood samples collected during a drug efficacy trial in Rwanda. Fifty percent of the infections classified as recrudescent by MSP were classified as new by microsatellite markers. Reciprocally, 23.3% of infections classified as recrudescent by microsatellite markers were identified as new by MSP. In drug efficacy studies, microsatellite markers should complement MSP genotyping to distinguish a recrudescence from a new infection

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