Biomedical subjects
K H Tennekoon
Publications and source records attributed to K H Tennekoon.
Possible hepatotoxicity of Nigella sativa seeds and Dregea volubilis leaves.
Aqueous extracts of the seeds of Nigella sativa and mature leaves of Dregea volubilis were administered orally under light ether anaesthesia to male Sprague-Dawley rats for 14 days. Key hepatic enzyme concentrations and histopathological changes in the liver in both treatment groups at the end of 14 days were compared with a control group which received distilled water under identical conditions for 30 days and with a group of normal animals. Serum gamma-glutamyl transferase concentrations were significantly increased in both extract groups while serum alkaline phosphatase concentrations were significantly increased following administration of only D. volubilis when compared with either the control or the normal group. Serum alanine aminotransferase concentrations were significantly increased in both extract groups when compared with the normal group but not with the control group. Degenerative changes in hepatocytes were seen following administration of D. volubilis while consistent significant histopathological changes were not evident following administration of N. sativa.
Time series analysis of biologically active luteinizing hormone concentrations during different stages of the menstrual cycle.
The biologically active luteinizing hormone concentrations (as measured by testosterone production by mouse Leydig cells in response to LH) were measured in integrated hourly blood samples collected over 24-hour study periods during different stages of the menstrual cycle from a group of regularly cyclic women. Time series analyses were used to analyse the ultradian rhythms in each individual 24-hour LH profile. Fast Fourier transform (FFT) showed the presence of several ultradian rhythms with different periodicities (varying from 4.4 to 22 hours) in most of the LH profiles. In some of the LH profiles several ultradian rhythms appeared to co-exist. The commonest significant rhythm as detected by the FFT had a periodicity of 7-9 hours during both the follicular phase (40% of the subjects) and the mid cycle (50% of the subjects) and a periodicity of 5-7 hours during the luteal phase (44% of the subjects).
Effect of Momordica charantia fruit juice on streptozotocin-induced diabetes in rats.
The oral hypoglycaemic activity of Momordica charantia fruit juice was investigated in rats with streptozotocin-induced diabetes. Oral administration of the juice (10 ml/kg for 30 days) did not show a significant effect, either acute or cumulative, on the ability to tolerate an external glucose load. The glycosylated haemoglobin concentrations were significantly elevated in both juice-treated and untreated diabetic rats and there was no significant difference between the two groups. Viable beta-cells capable of secreting insulin upon stimulation appear to be required for M. charantia to exert its oral hypoglycaemic activity.
A rise in the biologically active LH: immunologically active LH (B/I) ratio during the normal luteal phase.
Biologically active (bio) LH concentrations and immunologically active (immuno) LH concentrations were measured in integrated hourly blood samples collected over 24 h study periods (n = 27) and in 5 min blood samples collected over 2 h study periods (n = 21) during different stages of the menstrual cycle in a group of regularly cyclic women. Episodic fluctuations were seen in both the bio LH and immuno LH concentrations in hourly as well as in 5 min data series. However, there was no consistent correlation between episodes of bio LH and immuno LH. Mean B/I ratio over the 24 h study periods as well as over the 2 h study periods were significantly higher during the luteal phase than during either the follicular phase (p less than 0.002) or the mid cycle (p less than 0.02).
Prolactin concentrations during the normal menstrual cycle: rhythms within rhythms.
Prolactin concentrations were measured in frequent blood samples collected over a 2 h period randomly distributed during day and night, during the follicular and the luteal phases of the normal menstrual cycle in women. Episodic fluctuations in prolactin concentrations were observed throughout the 24 h period and the pattern of these fluctuations appeared to vary depending on the time, and sleep wake state. Thus a changing pattern of the 'primary pulse' of prolactin may be responsible for the time related and sleep related changes in prolactin during the 24 h period.