Atunga Nyachieo

Uterus transplantation in the baboon: methodology and long-term function after auto-transplantation

BACKGROUND 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. METHODS Female baboons (n = 15) underwent surgery, with the initial five animals used for studies of pelvic vascular anatomy. Retrieval surgery included isolation of the ovarian veins and the uterine arteries together with the anterior branches of the internal iliacs. The utero-tubal-ovarian specimen was removed, flushed and kept ex vivo for 2 h when the two arterial ends and two venous ends were anastomosed side-to-side to construct one arterial and one venous end. These were, at auto-transplantation, anastomosed end-to-side to the external iliacs and the animals (n = 10) were evaluated concerning cyclicity and later by laparoscopy/laparotomy. RESULTS The total duration of organ retrieval, backtable preparation and transplantation was around 6 h with an overall ischaemic time of the specimen of about 3 h. One animal died due to cardiomyopathy. Five out of the nine surviving animals resumed cyclicity, as a sign of re-established ovarian function. Only two out of these five animals exhibited resumed menstruation, indicating re-established ovarian and uterine function. Laparoscopy confirmed normal-sized uteri in these two animals. CONCLUSIONS This study demonstrates the feasibility of UTx by vascular anastomosis in a non-human primate species. The low success rate demonstrates the complexity involved in UTx surgery and the need for further methodological developments.

Cyclospora papionis, Cryptosporidium hominis, and Human-Pathogenic Enterocytozoon bieneusi in Captive Baboons in Kenya

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.

The detection of enteric viruses in selected urban and rural river water and sewage in Kenya, with special reference to rotaviruses

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

The Baboon as a Research Model for the Study of Endometrial Biology, Uterine Receptivity and Embryo Implantation

The process of embryo implantation includes attachment of the embryo to the endometrium and penetration through the epithelial layer, decidualization of the basement membrane, invasion of the uterine stroma and access to blood supply. This implantation process is very different in humans when compared to pigs, cattle or rodents. The process of invasion in humans where the embryo gets embedded in decidual tissue and in spiral arteries is more aggressive, but otherwise similar to the process of implantation and invasion in non-human primates such as rhesus monkeys and baboons. For ethical reasons, it is unacceptable to study directly the process of embryo implantation in women, and to this day, this remains one of the ‘black boxes’ of reproductive science. Indeed for many clinicians practicing reproductive medicine, in fertility centers, the most difficult question and of concern asked by patients is: ‘Why do my healthy appearing embryos not implant: is there a problem with my endometrium or uterus?’ The olive baboon (Papio anubis anubis) is an excellent animal model for reproductive research. In contrast with smaller non-human primates like rhesus monkeys or cynomolgus monkeys, it is possible in baboons to use transcervical uterine probes (curettes, catheters and hysteroscopic equipment) to perform endometrial biopsy, embryo flushing or transfer and hysteroscopy in a non-invasive way. This can be done easily in multiparous baboons during menstruation, but may be more difficult at the end of the follicular phase (maximal perineal swelling impedes vaginal/cervical access) or during the luteal phase (narrow cervix), in nulliparous baboons and in animals with abnormal internal genitals. In this paper we present an overview regarding the potential of the baboon model to study in vivo uterine receptivity and embryo implantation using invasive and non-invasive approaches.

The Epidemiology of Human Rotavirus Associated with Diarrhoea in Kenyan Children: A Review

Rotavirus gastroenteritis still remains a major cause of morbidity and mortality among young children in developing countries, with approximately 150,000-200,000 deaths occurring annually in sub-Saharan Africa. We reviewed papers published over the last 30 years on the epidemiology of rotavirus diarrhoea among the hospitalized and out-patient children in Kenya. The analysis shows rotavirus prevalence of 6-56% with diarrhoea occurring throughout the year and generally exhibiting distinct peaks during the dry months. Among the common genotype, G1 was the most predominant up to the year 2002 but more recently there has been an emergence of genotype G9 as the most predominant genotype and to a less extent G8. It is important to continue rotavirus surveillance in Kenya to determine accurately the burden of rotavirus disease and the emerging new genotypes. This will assist policy makers in decision making on rotavirus vaccine introduction and determining the impact of the vaccine.

Rotavirus G and P types circulating in the eastern region of Kenya: predominance of G9 and emergence of G12 genotypes.

Background: The World Health Organization has recommended that rotavirus (RV) vaccines be included in all national immunization programs as part of a strategy to control RV-associated diarrheal diseases. Hospital-based surveillance of RV infection is therefore crucial in monitoring the impact pre- and post-vaccine introduction and also to document changes in genotype distribution. This study sought to determine the RV genotypes circulating in the eastern region of Kenya before introduction of the RV vaccine. Methods: During September 2009 to August 2011, 500 stool samples were collected from children <5 years of age admitted for acute diarrhea in hospitals in the eastern region of Kenya and analyzed for the presence of group A RV using an enzyme immunoassay. G and P genotypes were determined using hemi-nested reverse transcriptase polymerase chain reaction. Results: One hundred and eighty nine out of 500 (38%) samples analyzed were positive for rotavirus. The following G types were detected: G9 (50.9%), G1 (26.8%), G8 (12.1%), G12 (3.1%), G2 (0.6%), mixed G (1.3%) and 5.1% were G nontypeable. P types detected included: P[8] (63.7%), P[4] (12.1%), P[6] (4.5%), mixed P (7.6%) and 12.1% were P nontypeable. The most dominant strain was G9P[8] (35%), followed by G1P[8] (26.8%), G8P[4] (9.6%), G12P[6] (2.5%), G9P[6] (1.9%), G9P[4] (1.3%), G8P[8] (1.3%), and G2P[4] (0.6%). Conclusions: The present study demonstrates the recurring changing genotypes of RV circulating in Kenya, with genotypes G9, G1 and G8 being the dominant strains circulating in the eastern region of Kenya between 2009 and 2011. Additionally, G12 genotype was detected for the first time in Kenya.

Menstrual cycle synchronization, ovarian stimulation, and in vitro fertilization in olive baboons (Papio anubis): a prospective randomized study.

OBJECTIVE To synchronize the baboon menstrual cycle and to compare different methods of ovarian stimulation for IVF in baboons. DESIGN Prospective randomized study. SETTING Institute of Primate Research, Nairobi, Kenya. ANIMAL(S) Ten female baboons were treated with an oral contraceptive (33 +/- 8 days) and randomized for ovarian stimulation in two cycles. INTERVENTION(S) In cycle 1 (C1), baboons were stimulated as follows: clomiphene citrate (CC) for 5 days followed by antagonist (group CC-1, n = 3); recombinant gonadotropins (rGn: rFSH and rLH) with antagonist (group antagon-1, n = 3); and long GnRH agonist protocol (group LP-1, n = 4). After 1- month rest, in cycle 2 (C2), the baboons were stimulated as follows: CC for 8 days without antagonist (group CC-2, n = 2); short GnRH agonist protocol (group SP-2, n = 4); long GnRH agonist protocol (group LP-2, n = 4). Oocyte aspiration was performed 34-36 hours after injecting 5000 IU recombinant hCG; the oocytes were then fertilized. MAIN OUTCOME MEASURE(S) Oocytes retrieved and fertilization rate. RESULT(S) Withdrawal bleeding occurred 4 +/- 1 days after the cessation of the contraceptive. Ovarian stimulation using the different protocols resulted in the following mean numbers of retrieved oocytes: LP-1, n = 19; LP-2, n = 19; CC-1, n = 4; CC-2, n = 4; antagon-1, n = 9; and SP-2, n = 14. Fertilization by intracytoplasmic sperm injection varied (23%-54%). CONCLUSION(S) The baboon menstrual cycle can be synchronized using an oral contraceptive. A long GnRH agonist protocol for ovarian stimulation may be suitable for ovarian stimulation in baboons.

Rotavirus infections among HIV-infected children in Nairobi Kenya.

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.

Improving ovarian stimulation protocols for IVF in baboons: Lessons from humans and rhesus monkeys

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.

Ovarian Tissue Cryopreservation by Vitrification in Olive Baboons (Papio Anubis): A Pilot Study

Background: 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. Methods: Ovarian cortical tissues (1-mm cubes) were obtained surgically from adult female olive baboons (n = 9) maintained in captivity and vitrified using dimethyl sulphoxide and ethylene glycol protocol. The proportion of morphologically intact follicles (primordial, primary and secondary) in paired fresh and cryopreserved (vitrified-thawed) ovarian tissues was compared. Results: Overall, 67.1% of follicles were morphologically normal after vitrification. When compared to fresh ovarian tissue, vitrified-thawed ovarian tissue contained a comparable number of intact primordial follicles (48.9 vs. 52.9%), and a lower number of both primary (14.8 vs. 29.5%; p < 0.05) and secondary (2.0 vs. 0.7%; p < 0.05) follicles. Conclusion: After vitrification and thawing, baboon ovarian tissue retains about 67% of morphologically normal follicles, which is comparable to results for human ovarian tissue, and suggests that the olive baboon is a promising animal model for preclinical assessment of ovarian vitrification, thawing and autotransplantation studies.