Bio

DR. ONYANGO DANIEL W .

Dr. Onyango was born in 1958 in Siaya County, Kenya. He obtained his early education in the local county schools namely Lusi Primary and Maranda High School from where he proceeded to Nkubu High School, Meru County for A-levels. He subsequently joined the Faculty of Veterinary Medicine, University of Nairobi from where he graduated with a Bachelor of Veterinary Medicine degree in 1986.

Publications


2014

2012

PAPAH, DRMICHAELBABAK, MARANDE PROFKISIASETH, OMONDI DROJOORODI, NDEGWA DRMAKANYAANDREW,. DRONYANGODANIELW.  2012.  The structure of the male reproductive organs in lake magadi tilapia (Alcolapia grahami); a fish living on the edge. TWAS-BiovisionAlexandria NXT Conference, Alexandria Egypt.. : Elsevier
PAPAH, DRMICHAELBABAK, MARANDE PROFKISIASETH, NDEGWA DRMAKANYAANDREW,. DRONYANGODANIELW.  2012.  Spermiogenesis and sperm ultrastructure of Lake Magadi tilapia Alcolapia grahami (Teleostei, Perciformes, Cichlidae). Joint Faculty of Veterinary Medicine 8th Biennial Scientific Conference and 46th Kenya Veterinary Association annual Scientific conference, Nairobi. : Elsevier
MARANDE, PROFKISIASETH, OMONDI DROJOORODI, NDEGWA DRMAKANYAANDREW,. DRONYANGODANIELW.  2012.  Spermiogenesis and sperm ultrastructure of Lake Magadi tilapia Alcolapia grahami (Teleostei, Perciformes, Cichlidae). Joint Faculty of Veterinary Medicine 8th Biennial Scientific Conference and 46th Kenya Veterinary Association Annual Scientific Conference. : Elsevier
MARANDE, PROFKISIASETH, OMONDI DROJOORODI, NDEGWA DRMAKANYAANDREW,. DRONYANGODANIELW.  2012.  The structure of the male reproductive organs in Lake Magadi tilapia (Alcolapia grahami); a fish living on the edge.. TWAS/BiovisionAlexandria. NXT Conference. Alexandria Egypt. : Elsevier

2011

Onyango, DW, Oduor-Okelo D, Makanya AN;, Kisipan ML.  2011.  The Functional Morphology and Adaptations of the Epididymis in a Testicndid Mammal, The Rufous Sengi (Elephantulus rufescens).. Abstract

Sengis are testicondid African mammals that constitute Order Macroscelidae. The epididymal mo rphology in the rufous sengis ( Elephantulus rufescens ) was studied with focus on features and adaptations that make it suitable for sperm maturation and storage in this testicondid mammal. The three topographic regions were distinct with the caput and cau da epididymis placed far apart, connected by a slender corpus. The caput occurred as a longitudinal mass on the dorsolateral border of the testis while the Cauda, pear shaped mass, was laterally placed between the rectum and the pelvic urethra. The epidid ymal epithelium comprised principal and basal cells; the former exhibiting granules and apical blebbing in the caput. The lumen of the cauda was densely packed with spermatozoa that are occasionally wrapped by amorphous dark masses, and its principal cells had numerous vacuoles. This study demonstrates that beside merocrine secretion, principal cells of sengi’s caput also exhibit apocrine secretion as shown by apical blebs. The blebs are shed off plausibly as a means of delivering epididymosomes to the lum en, which in turn transfer epididymis secreted proteins to the spermatozoa. Additionally, the study has shown that the cauda epididymis descends to a site probably cooler than the core body temperature for optimal sperm storage, with the vacuoles indicatin g its involvement in fluid re absorption and phagocytosis.

2010

2009

LETURA, DRKISIPANMOSIANY, NDEGWA DRMAKANYAANDREW,. DRONYANGODANIELW, ODUOR PROFOKELLODOMINIC.  2009.  The morphology and morphometry of the male reproductive system of the rufous sengi (Elephantulus rufescens).. MSc. Thesis, University of Nairobi. : Kisipan, M.L.

2008

2007

2006

2005

., DRONYANGODANIELW.  2005.  Ojoo, R. O., Otiang. MSc. Thesis, University of Nairobi. : Kisipan, M.L. Abstract

Isolated mouse interstitial cells were incubated with different concentrations of khat (Catha edulis) extract (0.06 mg/ml, 0.6 mg/ml. 6 mg/ml. 30 mg/ml and 60 mg/ml) and cell viability as well as testosterone concentration measured at 30 min intervals over a 3 h incubation period. High concentrations of khat extract (30 mg/ml and 60 mg/ml) significantly inhibited testosterone production while low concentrations (0.06 mg/ml. 0.6 mg/ml and 6 mg/ml) significantly stimulated (P < 0.05) testosterone production by mouse interstitial cells. Similarly, at concentrations of 30 mg/ml and 60 mg/ml, there was a significant decrease in interstitial cell viability, whereas at 0.06 mg/ml, 0.6 mg/ml and 6 mg/ml there was no significant decrease. There was only a weak correlation (r= 0.39) between testosterone production and viable interstitial cells. We postulate that khat extract at high concentrations may cause reproductive function impairment in the user but at low concentrations. may enhance testosterone production with accompanying effects on reproductive functions in male mice. @2006 Publishedby Elsevier Ireland Ltd. Kel'lVords: In dtro; Khat; Testosterone; Interstitial cells; Mouse

., DRONYANGODANIELW.  2005.  Kisia, S. M and Onyango, D. W (2005): Muscular System of Vertebrates,Science Publishers Inc., Enfield, New Hampshire, USA.. MSc. Thesis, University of Nairobi. : Kisipan, M.L. Abstract

Isolated mouse interstitial cells were incubated with different concentrations of khat (Catha edulis) extract (0.06 mg/ml, 0.6 mg/ml. 6 mg/ml. 30 mg/ml and 60 mg/ml) and cell viability as well as testosterone concentration measured at 30 min intervals over a 3 h incubation period. High concentrations of khat extract (30 mg/ml and 60 mg/ml) significantly inhibited testosterone production while low concentrations (0.06 mg/ml. 0.6 mg/ml and 6 mg/ml) significantly stimulated (P < 0.05) testosterone production by mouse interstitial cells. Similarly, at concentrations of 30 mg/ml and 60 mg/ml, there was a significant decrease in interstitial cell viability, whereas at 0.06 mg/ml, 0.6 mg/ml and 6 mg/ml there was no significant decrease. There was only a weak correlation (r= 0.39) between testosterone production and viable interstitial cells. We postulate that khat extract at high concentrations may cause reproductive function impairment in the user but at low concentrations. may enhance testosterone production with accompanying effects on reproductive functions in male mice. @2006 Publishedby Elsevier Ireland Ltd. Kel'lVords: In dtro; Khat; Testosterone; Interstitial cells; Mouse

2001

., DRONYANGODANIELW.  2001.  Onyango, D. W., Wango, E. O and Werner, G (2001): Epididymal epithelial cell involution following a single intraperitoneal administration of ethane dimethanesulphonate (EDS) in the goat (Capra hircus). Toxicol. Appl. Pharmacol. 175(1): 19-27.. MSc. Thesis, University of Nairobi. : Kisipan, M.L. Abstract

Isolated mouse interstitial cells were incubated with different concentrations of khat (Catha edulis) extract (0.06 mg/ml, 0.6 mg/ml. 6 mg/ml. 30 mg/ml and 60 mg/ml) and cell viability as well as testosterone concentration measured at 30 min intervals over a 3 h incubation period. High concentrations of khat extract (30 mg/ml and 60 mg/ml) significantly inhibited testosterone production while low concentrations (0.06 mg/ml. 0.6 mg/ml and 6 mg/ml) significantly stimulated (P < 0.05) testosterone production by mouse interstitial cells. Similarly, at concentrations of 30 mg/ml and 60 mg/ml, there was a significant decrease in interstitial cell viability, whereas at 0.06 mg/ml, 0.6 mg/ml and 6 mg/ml there was no significant decrease. There was only a weak correlation (r= 0.39) between testosterone production and viable interstitial cells. We postulate that khat extract at high concentrations may cause reproductive function impairment in the user but at low concentrations. may enhance testosterone production with accompanying effects on reproductive functions in male mice. @2006 Publishedby Elsevier Ireland Ltd. Kel'lVords: In dtro; Khat; Testosterone; Interstitial cells; Mouse

., DRONYANGODANIELW.  2001.  Onyango, D. W., Wango, E. O., Oduor-Okelo, D and Werner, G (2001): Early testicular response to intraperitoneal administration of ethane dimethanesulphonate (EDS) in the goat (Capra hircus). J. Submicrosc.Cytol. Pathol., 33(1-2): 117-124.. MSc. Thesis, University of Nairobi. : Kisipan, M.L. Abstract

Isolated mouse interstitial cells were incubated with different concentrations of khat (Catha edulis) extract (0.06 mg/ml, 0.6 mg/ml. 6 mg/ml. 30 mg/ml and 60 mg/ml) and cell viability as well as testosterone concentration measured at 30 min intervals over a 3 h incubation period. High concentrations of khat extract (30 mg/ml and 60 mg/ml) significantly inhibited testosterone production while low concentrations (0.06 mg/ml. 0.6 mg/ml and 6 mg/ml) significantly stimulated (P < 0.05) testosterone production by mouse interstitial cells. Similarly, at concentrations of 30 mg/ml and 60 mg/ml, there was a significant decrease in interstitial cell viability, whereas at 0.06 mg/ml, 0.6 mg/ml and 6 mg/ml there was no significant decrease. There was only a weak correlation (r= 0.39) between testosterone production and viable interstitial cells. We postulate that khat extract at high concentrations may cause reproductive function impairment in the user but at low concentrations. may enhance testosterone production with accompanying effects on reproductive functions in male mice. @2006 Publishedby Elsevier Ireland Ltd. Kel'lVords: In dtro; Khat; Testosterone; Interstitial cells; Mouse

., DRONYANGODANIELW.  2001.  Onyango, D. W (2001): Effects of ethane dimethanesulphonate (EDS) on testicular and epididymal structure, and plasma testosterone profiles in the goat (Capra hircus). Ph.D thesis, University of Nairobi, Kenya.. MSc. Thesis, University of Nairobi. : Kisipan, M.L. Abstract

Isolated mouse interstitial cells were incubated with different concentrations of khat (Catha edulis) extract (0.06 mg/ml, 0.6 mg/ml. 6 mg/ml. 30 mg/ml and 60 mg/ml) and cell viability as well as testosterone concentration measured at 30 min intervals over a 3 h incubation period. High concentrations of khat extract (30 mg/ml and 60 mg/ml) significantly inhibited testosterone production while low concentrations (0.06 mg/ml. 0.6 mg/ml and 6 mg/ml) significantly stimulated (P < 0.05) testosterone production by mouse interstitial cells. Similarly, at concentrations of 30 mg/ml and 60 mg/ml, there was a significant decrease in interstitial cell viability, whereas at 0.06 mg/ml, 0.6 mg/ml and 6 mg/ml there was no significant decrease. There was only a weak correlation (r= 0.39) between testosterone production and viable interstitial cells. We postulate that khat extract at high concentrations may cause reproductive function impairment in the user but at low concentrations. may enhance testosterone production with accompanying effects on reproductive functions in male mice. @2006 Publishedby Elsevier Ireland Ltd. Kel'lVords: In dtro; Khat; Testosterone; Interstitial cells; Mouse

2000

Werner, G, Oduor-Okelo D, Otiang'a-owiti GE, Wango EO, Onyango DW.  2000.  Morphological characterization of the seminiferous cycle in the goat (Capra hircus): A histological and ultrastructural study. Abstract

The cycle of spermatogenesis/seminiferous cycle was investigated in the goat testis using both light and electron microscopy techniques. Using the various cell associations and the accompanying changes in spermatid shape and location, the cycle was divided into eight (8) successive stages. The cycle began with the accomplishment of spermiation (stage 1) and ended with apical migration and close attachment of late maturation phase spermatids at the Sertoli cell apex accompanied by adluminal retention of residual bodies with dense staining inclusions (stage 8). The early stages of the cycle (stages 1–4) were therefore characterized by the presence of only one generation of spermatids, the second one appearing only after the division of secondary spermatocytes in stage 4. Consequently, stages 5–8 had two generations of spermatids; Golgi or cap phase as well as maturation phase spermatids. Although stages 5 to 7 appeared as distinct entities, stages 6 and 7 were rather short-lived and considered as continuations of stage 5. Therefore, the 8 stages of the cycle in the goat were further condensed into 6 main divisions. The duration of each stage was estimated by the frequency of occurrence in sections. Among these, stage 1 had the highest frequency (34%) followed by stages 5–7 (27%). Stages 8 and 4 had the shortest frequency (up to 9%) while stages 2 and 3 had 13% and 12% respectively. These results indicate that, like most domestic species, goats have a cycle of 8 stages with 6 main divisions, the longest being stage 1.

., DRONYANGODANIELW.  2000.  Otiang'a-Owiti, G. E., Onyango, D. W., Ouma, J. O., Njogu, A and Mungania, S.K (2000): A review on methods employed in studying embryogenesis. AJST, 1(3):38-43.. MSc. Thesis, University of Nairobi. : Kisipan, M.L. Abstract

Isolated mouse interstitial cells were incubated with different concentrations of khat (Catha edulis) extract (0.06 mg/ml, 0.6 mg/ml. 6 mg/ml. 30 mg/ml and 60 mg/ml) and cell viability as well as testosterone concentration measured at 30 min intervals over a 3 h incubation period. High concentrations of khat extract (30 mg/ml and 60 mg/ml) significantly inhibited testosterone production while low concentrations (0.06 mg/ml. 0.6 mg/ml and 6 mg/ml) significantly stimulated (P < 0.05) testosterone production by mouse interstitial cells. Similarly, at concentrations of 30 mg/ml and 60 mg/ml, there was a significant decrease in interstitial cell viability, whereas at 0.06 mg/ml, 0.6 mg/ml and 6 mg/ml there was no significant decrease. There was only a weak correlation (r= 0.39) between testosterone production and viable interstitial cells. We postulate that khat extract at high concentrations may cause reproductive function impairment in the user but at low concentrations. may enhance testosterone production with accompanying effects on reproductive functions in male mice. @2006 Publishedby Elsevier Ireland Ltd. Kel'lVords: In dtro; Khat; Testosterone; Interstitial cells; Mouse

., DRONYANGODANIELW.  2000.  Onyango, D. W., Wango, E. O., Otiang. MSc. Thesis, University of Nairobi. : Kisipan, M.L. Abstract

Isolated mouse interstitial cells were incubated with different concentrations of khat (Catha edulis) extract (0.06 mg/ml, 0.6 mg/ml. 6 mg/ml. 30 mg/ml and 60 mg/ml) and cell viability as well as testosterone concentration measured at 30 min intervals over a 3 h incubation period. High concentrations of khat extract (30 mg/ml and 60 mg/ml) significantly inhibited testosterone production while low concentrations (0.06 mg/ml. 0.6 mg/ml and 6 mg/ml) significantly stimulated (P < 0.05) testosterone production by mouse interstitial cells. Similarly, at concentrations of 30 mg/ml and 60 mg/ml, there was a significant decrease in interstitial cell viability, whereas at 0.06 mg/ml, 0.6 mg/ml and 6 mg/ml there was no significant decrease. There was only a weak correlation (r= 0.39) between testosterone production and viable interstitial cells. We postulate that khat extract at high concentrations may cause reproductive function impairment in the user but at low concentrations. may enhance testosterone production with accompanying effects on reproductive functions in male mice. @2006 Publishedby Elsevier Ireland Ltd. Kel'lVords: In dtro; Khat; Testosterone; Interstitial cells; Mouse

1998

Onyango, DW;, Wango EO;, Odongo H;, Mugweru J;, Okindo E.  1998.  Effects Of Heptachlor On Rat Plasma LH, Testosterone And Cortisol Levels, And Testicular Structure..
., DRONYANGODANIELW.  1998.  Onyango, D. W., Wango, E. O. Odongo, H., Mugweru, J & Okindo, E (1998):Effects of heptachlor on rat plasma LH, testosterone and cortisol and testicular structure. In;. Proceedings of the First Meeting of Federation of African Societies of Biochemistry and Molecular Biology(FASBMB) (Eds. Ochanda, J. O., Kiaira, J. K & Makawiti, D. W.),pp.195-198. Biochemical Society of Kenya.. : Kisipan, M.L. Abstract

Isolated mouse interstitial cells were incubated with different concentrations of khat (Catha edulis) extract (0.06 mg/ml, 0.6 mg/ml. 6 mg/ml. 30 mg/ml and 60 mg/ml) and cell viability as well as testosterone concentration measured at 30 min intervals over a 3 h incubation period. High concentrations of khat extract (30 mg/ml and 60 mg/ml) significantly inhibited testosterone production while low concentrations (0.06 mg/ml. 0.6 mg/ml and 6 mg/ml) significantly stimulated (P < 0.05) testosterone production by mouse interstitial cells. Similarly, at concentrations of 30 mg/ml and 60 mg/ml, there was a significant decrease in interstitial cell viability, whereas at 0.06 mg/ml, 0.6 mg/ml and 6 mg/ml there was no significant decrease. There was only a weak correlation (r= 0.39) between testosterone production and viable interstitial cells. We postulate that khat extract at high concentrations may cause reproductive function impairment in the user but at low concentrations. may enhance testosterone production with accompanying effects on reproductive functions in male mice. @2006 Publishedby Elsevier Ireland Ltd. Kel'lVords: In dtro; Khat; Testosterone; Interstitial cells; Mouse

1997

., DRONYANGODANIELW.  1997.  Wango, E. O., Onyango, D. W., Odongo, H., Okindo, E & Mugweru, J (1997):In vitro production of testosterone and plasma levels of luteinizing hormone, testosterone and cortisol in male rats treated with heptachlor.Comp. Biochem. Physiol., 118C(3): 381-386.. Proceedings of the First Meeting of Federation of African Societies of Biochemistry and Molecular Biology(FASBMB) (Eds. Ochanda, J. O., Kiaira, J. K & Makawiti, D. W.),pp.195-198. Biochemical Society of Kenya.. : Kisipan, M.L. Abstract

Isolated mouse interstitial cells were incubated with different concentrations of khat (Catha edulis) extract (0.06 mg/ml, 0.6 mg/ml. 6 mg/ml. 30 mg/ml and 60 mg/ml) and cell viability as well as testosterone concentration measured at 30 min intervals over a 3 h incubation period. High concentrations of khat extract (30 mg/ml and 60 mg/ml) significantly inhibited testosterone production while low concentrations (0.06 mg/ml. 0.6 mg/ml and 6 mg/ml) significantly stimulated (P < 0.05) testosterone production by mouse interstitial cells. Similarly, at concentrations of 30 mg/ml and 60 mg/ml, there was a significant decrease in interstitial cell viability, whereas at 0.06 mg/ml, 0.6 mg/ml and 6 mg/ml there was no significant decrease. There was only a weak correlation (r= 0.39) between testosterone production and viable interstitial cells. We postulate that khat extract at high concentrations may cause reproductive function impairment in the user but at low concentrations. may enhance testosterone production with accompanying effects on reproductive functions in male mice. @2006 Publishedby Elsevier Ireland Ltd. Kel'lVords: In dtro; Khat; Testosterone; Interstitial cells; Mouse

1995

Hendrickx, AG, Otiang'a-owiti GE, Gachoka JM, Onyango DW.  1995.  Seasonally dependent testicular apoptosis in the tropical Long-fingered bat (Miniopterus inflatus). Abstract

Testicular morphology of long-fingered bats trapped in March and early April (a period of sexual dormancy) was studied using both light and electron microscopy. The interstitial tissue, generally smaller in proportion to the seminiferous tubules, was largely made up of compactly arranged interstitial (Leydig) cells. Physiological cell death (apoptosis) was characterized by the occurrence of dense cytoplasm obscuring most of the subcellular organelles, myelin-like whorls of residual bodies and lipid inclusions in the cytoplasm, and roughly spheroidal nuclei. Normal mitochondria were round in outline. Some of these apoptotic cells were phagocytosed by the interstitial tissue macrophages. In the seminiferous tubules this degenerative process was marked by spermatogonial karyolysis, apoptosis of spermatocytes and extensive accumulation of large lipid droplets in the Sertoli cell cytoplasm. The tubular walls and lumen were completely devoid of spermatids and spermatozoa. These observations suggest that the sexual dormancy in these bats is characterized by a marked apoptosis of testicular micro-structural components hitherto unreported.

., DRONYANGODANIELW.  1995.  Onyango, D. W., Gachoka, J. M., Otiang. Proceedings of the First Meeting of Federation of African Societies of Biochemistry and Molecular Biology(FASBMB) (Eds. Ochanda, J. O., Kiaira, J. K & Makawiti, D. W.),pp.195-198. Biochemical Society of Kenya.. : Kisipan, M.L. Abstract

Isolated mouse interstitial cells were incubated with different concentrations of khat (Catha edulis) extract (0.06 mg/ml, 0.6 mg/ml. 6 mg/ml. 30 mg/ml and 60 mg/ml) and cell viability as well as testosterone concentration measured at 30 min intervals over a 3 h incubation period. High concentrations of khat extract (30 mg/ml and 60 mg/ml) significantly inhibited testosterone production while low concentrations (0.06 mg/ml. 0.6 mg/ml and 6 mg/ml) significantly stimulated (P < 0.05) testosterone production by mouse interstitial cells. Similarly, at concentrations of 30 mg/ml and 60 mg/ml, there was a significant decrease in interstitial cell viability, whereas at 0.06 mg/ml, 0.6 mg/ml and 6 mg/ml there was no significant decrease. There was only a weak correlation (r= 0.39) between testosterone production and viable interstitial cells. We postulate that khat extract at high concentrations may cause reproductive function impairment in the user but at low concentrations. may enhance testosterone production with accompanying effects on reproductive functions in male mice. @2006 Publishedby Elsevier Ireland Ltd. Kel'lVords: In dtro; Khat; Testosterone; Interstitial cells; Mouse

1993

., DRONYANGODANIELW.  1993.  Onyango, D. W., Oduor-Okelo, D & Otiang. Proceedings of the First Meeting of Federation of African Societies of Biochemistry and Molecular Biology(FASBMB) (Eds. Ochanda, J. O., Kiaira, J. K & Makawiti, D. W.),pp.195-198. Biochemical Society of Kenya.. : Kisipan, M.L. Abstract

Isolated mouse interstitial cells were incubated with different concentrations of khat (Catha edulis) extract (0.06 mg/ml, 0.6 mg/ml. 6 mg/ml. 30 mg/ml and 60 mg/ml) and cell viability as well as testosterone concentration measured at 30 min intervals over a 3 h incubation period. High concentrations of khat extract (30 mg/ml and 60 mg/ml) significantly inhibited testosterone production while low concentrations (0.06 mg/ml. 0.6 mg/ml and 6 mg/ml) significantly stimulated (P < 0.05) testosterone production by mouse interstitial cells. Similarly, at concentrations of 30 mg/ml and 60 mg/ml, there was a significant decrease in interstitial cell viability, whereas at 0.06 mg/ml, 0.6 mg/ml and 6 mg/ml there was no significant decrease. There was only a weak correlation (r= 0.39) between testosterone production and viable interstitial cells. We postulate that khat extract at high concentrations may cause reproductive function impairment in the user but at low concentrations. may enhance testosterone production with accompanying effects on reproductive functions in male mice. @2006 Publishedby Elsevier Ireland Ltd. Kel'lVords: In dtro; Khat; Testosterone; Interstitial cells; Mouse

1992

., DRONYANGODANIELW.  1992.  Onyango, D. W (1992): Histological and ultrastructural study of the male reproductive system of non-breeding naked mole rats (Heterocephalus glaber, Ruppell) and in vitro interstitial (Leydig) cell response to luteinizing hormone (LH). MSc. thesis,univers. Proceedings of the First Meeting of Federation of African Societies of Biochemistry and Molecular Biology(FASBMB) (Eds. Ochanda, J. O., Kiaira, J. K & Makawiti, D. W.),pp.195-198. Biochemical Society of Kenya.. : Kisipan, M.L. Abstract

Isolated mouse interstitial cells were incubated with different concentrations of khat (Catha edulis) extract (0.06 mg/ml, 0.6 mg/ml. 6 mg/ml. 30 mg/ml and 60 mg/ml) and cell viability as well as testosterone concentration measured at 30 min intervals over a 3 h incubation period. High concentrations of khat extract (30 mg/ml and 60 mg/ml) significantly inhibited testosterone production while low concentrations (0.06 mg/ml. 0.6 mg/ml and 6 mg/ml) significantly stimulated (P < 0.05) testosterone production by mouse interstitial cells. Similarly, at concentrations of 30 mg/ml and 60 mg/ml, there was a significant decrease in interstitial cell viability, whereas at 0.06 mg/ml, 0.6 mg/ml and 6 mg/ml there was no significant decrease. There was only a weak correlation (r= 0.39) between testosterone production and viable interstitial cells. We postulate that khat extract at high concentrations may cause reproductive function impairment in the user but at low concentrations. may enhance testosterone production with accompanying effects on reproductive functions in male mice. @2006 Publishedby Elsevier Ireland Ltd. Kel'lVords: In dtro; Khat; Testosterone; Interstitial cells; Mouse

., DRONYANGODANIELW.  1992.  Onyango, D. W., Oduor-Okelo, D & Otiang. Proceedings of the First Meeting of Federation of African Societies of Biochemistry and Molecular Biology(FASBMB) (Eds. Ochanda, J. O., Kiaira, J. K & Makawiti, D. W.),pp.195-198. Biochemical Society of Kenya.. : Kisipan, M.L. Abstract

Isolated mouse interstitial cells were incubated with different concentrations of khat (Catha edulis) extract (0.06 mg/ml, 0.6 mg/ml. 6 mg/ml. 30 mg/ml and 60 mg/ml) and cell viability as well as testosterone concentration measured at 30 min intervals over a 3 h incubation period. High concentrations of khat extract (30 mg/ml and 60 mg/ml) significantly inhibited testosterone production while low concentrations (0.06 mg/ml. 0.6 mg/ml and 6 mg/ml) significantly stimulated (P < 0.05) testosterone production by mouse interstitial cells. Similarly, at concentrations of 30 mg/ml and 60 mg/ml, there was a significant decrease in interstitial cell viability, whereas at 0.06 mg/ml, 0.6 mg/ml and 6 mg/ml there was no significant decrease. There was only a weak correlation (r= 0.39) between testosterone production and viable interstitial cells. We postulate that khat extract at high concentrations may cause reproductive function impairment in the user but at low concentrations. may enhance testosterone production with accompanying effects on reproductive functions in male mice. @2006 Publishedby Elsevier Ireland Ltd. Kel'lVords: In dtro; Khat; Testosterone; Interstitial cells; Mouse

1991

., DRONYANGODANIELW.  1991.  Onyango, D. W., Otiang. Proceedings of the First Meeting of Federation of African Societies of Biochemistry and Molecular Biology(FASBMB) (Eds. Ochanda, J. O., Kiaira, J. K & Makawiti, D. W.),pp.195-198. Biochemical Society of Kenya.. : Kisipan, M.L. Abstract

Isolated mouse interstitial cells were incubated with different concentrations of khat (Catha edulis) extract (0.06 mg/ml, 0.6 mg/ml. 6 mg/ml. 30 mg/ml and 60 mg/ml) and cell viability as well as testosterone concentration measured at 30 min intervals over a 3 h incubation period. High concentrations of khat extract (30 mg/ml and 60 mg/ml) significantly inhibited testosterone production while low concentrations (0.06 mg/ml. 0.6 mg/ml and 6 mg/ml) significantly stimulated (P < 0.05) testosterone production by mouse interstitial cells. Similarly, at concentrations of 30 mg/ml and 60 mg/ml, there was a significant decrease in interstitial cell viability, whereas at 0.06 mg/ml, 0.6 mg/ml and 6 mg/ml there was no significant decrease. There was only a weak correlation (r= 0.39) between testosterone production and viable interstitial cells. We postulate that khat extract at high concentrations may cause reproductive function impairment in the user but at low concentrations. may enhance testosterone production with accompanying effects on reproductive functions in male mice. @2006 Publishedby Elsevier Ireland Ltd. Kel'lVords: In dtro; Khat; Testosterone; Interstitial cells; Mouse

1982

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