9 Records out of 22207 Records

Gender physiology and the allocation of labor in subsistence households.

Author: Coleman, Susan Long

Awarding University: University of Hawaii, USA

Level : PhD

Year: 1997

Holding Libraries: University Microfilms International ;

Subject Terms: Labour economics ; Women's studies ; Metabolism ; Farming ;

Abstract:

This dissertation is a study of the inter-relationships between human physiology, the calorie costs of labor, and food production in the subsistence household with special emphasis on gender differences. Two economic models depicting the above relationships are formulated--one a cost minimizing model and the other a profit maximizing model. An empirical analysis follows which explores the effects of physiological and household characteristics on labor and calorie allocations using data from subsistence households in Kenya. The results of the study suggest: (1) physiological characteristics influence subsistence household labor and calorie allocation. (2) differences between males and females in the allocation of subsistence household labor and calorie allocation can be explained by physiological differences. (3) households may exhibit cost minimizing behavior that could lead to the perpetual overwork of women.

Metabolism of phosphoenol pyruvate derived from glucose catabolism by bloodstream Trypanosoma congolense.

Author: Odhiambo, J O

Awarding University: University of Nairobi, Kenya

Level : MSc

Year: 1996

Holding Libraries: University of Nairobi Jomo Kenyatta Memorial Library ;

Subject Terms: Trypanosoma congolense ; Metabolism ; Pyruvate kinase ; Glucose ;

Abstract:

The main purpose of this study was to establish the pathway(s) by which PEP from glucose catabolism is catabolized, the end products formed in the presence and absence of SHAM, the subcellular localisation of some key enzymes involved in PEP catabolism and to partially characterise PEPCK in bloodstream T. congolense. When the trypanosomes were incubated with glucose as the substrate in the absence of SHAM, the main end products observed were, acetate, glycerol and pyruvate. The amounts observed were 292.9 ? 56.3; 308 ?54 and 154 ? 19 nmoles/30 min/mg protein respectively. Addition of SHAM reduced the production of glycerol, acetate and pyruvate to 165 ? 36; 44.6 ? 30 and 26 ? 2 nmoles/30 min/mg protein respectively. Succinate which was not detectable in the absence of SHAM was found to be 1.32 ? 0.29 nmoles/30 min/mg protein. Lactate was not produced as an end product. It was therefore concluded that, under aerobic conditions, bloodstream T. congolense produce glycerol, acetate and pYl1!vate as the main end products of glucose catabolism. Under anaerobic conditions simulated by addition of SHAM, glycerol, acetate and pyruvate were still produced with succinate as a minor end product. The rate of respiration was also measured in the presence and absence of SHAM and cyanide. It was observed that SHAM totally inhibited the rate of respiration whereas cyanide had no effect. It was therefore proposed that molecular oxygen is the terminal electron acceptor whichreoxidises the reducing equivalents in (NADH) via the trypanosome alternate oxidase (TAO). The bloodstream T. congolense appears to have no cytochrome systems which could be inhibited by cyanide but has an alternative oxidase which was inhibited by SHAM. The amount of pyruvate production was determined in the presence of SHAM, cyanide or in their absence for 30 minutes. It was observed that in the absence of both SHAM and cyanide, 155?12 nmoles/30 minlmg protein was produced while in the presence of both SHAM and cyanide, only 28 ? 4 nmoles/30 minlmg protein was produced. When SHAM alone was present, ~:6 ? 8 nmoles/30 minlmg protein was produced while in the presence of cyanide alone 156 ? 12 nmoles/30 minlmg protein was produced. When the production of pyruvate was measured with time under aerobic conditions , there was an increase from 0 to 280 nmoles/mg protein after 3 hrs of incubation. The maximum quantity achieved in the presence of SHAM was 24 nmoles/mg protein. This was achieved after 30 minutes and remained constant for 3 hrs. This was attributed to death and lysis of the trypanosomes after 30 minutes in the presence of SHAM. It was concluded that bloodstream T congolense only possesses trypanosome alternate oxidase (TAO) as a means of oxidising the reducing equivalents. The activities of the enzymes likely to be involved in the catabolism of PEP derived from glucose oxidation to pyruvate were assayed. The enzymes which had specific activities greater than 36 nmoles/minlmg protein were PEP carboxykinase, NADP-linked malic enzyme and malate dehydrogenase. Those that had- specific activities less than 6 nmoles/minlmg protein were pyruvate kinase and NAD-linked malic enzyme. From these observations it was suggested that bloodstream T congolense catabolise PEP to pyruvate via another pathway not involving pyruvate kinase. It was also concluded that it was unlikely that pyruvate could be converted to lactate due to the low specific activity oflactate dehydrogenase of <0.43 nmoles/minlmg protein. The activities of the enzymes likely to catabolise pyruvate further to either acetate or TeA cycle intermediates were assayed. The enzymes which had specific activities greater than 18 nmoles/minlmg protein were fumarase, pyruvate dehydrogenase, phosphotransacetylase, acetate kinase and malate dehydrogenase. Those that had specific activities less than 2 nmoles/minlmg protein were aconitase, citrate synthase, a-ketoglutarate dehydrogenase and NADP-linked isocitrate dehydrogenase.

Nitrogen metabolism in the ostrich, (Struthio camelus)

Author: Orenge, Caleb Oburu

Awarding University: University of Nairobi, Kenya

Level : MSc

Year: 1995

Holding Libraries: University of Nairobi Jomo Kenyatta Memorial Library ;

Subject Terms: Nitrogen ; Ostrich USE Struthio camelus ; Struthio camelus ; Metabolism ;

Abstract:

The thriving of the ostrich in an otherwise very harsh environment has been an intriguing question to many people. The objective of this study was to find out some of the physiological explanations to this question. Some aspects of nitrogen metabolism were studied in the Ostrich: Maj or ur inary nitrogen me tabo lites in ostrich urine (uric acid nitrogen, urea nitrogen and ammonia ni trogen) were parti tioned. Plasma urea and urinary ammonia levels were also determined using commercial kits based on Berthelot's reaction while uric acid was determined by the decrease in absorbance at 292nm wavelenth before and after incubation with uricase. Nitrogen requirement for maintenance in these birds was determined by regressing apparently absorbed nitrogen on the retained nitrogen. The y-intercept of the regression equation gave the Nitrogen maintanance requirement. Nitrogen balance (the difference of nitrogen intake and nitrogen output (in faeces and in urine) was determined and used as a measure of efficiency of nitrogen metabolism. It was found that uric acid nitrogen was the most abundant (76.607. ; as in other birds) followed by urea nitrogen (10.207.). Ammonia nitrogen (2.37.) was the least, unlike in chicken where the proportion of urea nitrogen is least (37.). Nevertheless in absolute terms, ammonia nitrogen in the ostrich urine (2.37.) was lower than in chicken (77.). Efficiency of nitrogen retention and the rate of nitrogen retention were found to be 50.0 and 32 7.. respectively. An amount of 419 mg of ni trogen per metabolic body weight was found to be required to maintain zero nitrogen balance, a value that is lower than for sheep(ruminant) and higher than that for the horse (non-ruminants)It is concluded that, like other birds, an ostrich is uricotelic. The fact that the amount of ammonia excreted in the ostrich is less than in other birds may be a unique feature of the former and has a physiological backing as this may help to conserve water in the otherwise arid environment where it inhabits. Again, the apparently low nitrogen required for maintenance and the high efficiency of nitrogen retention recorded may be part of the explanation as to why the ostrich thrives in the arid and semi-arid environments where quality of grass and other herbage in terms of protein is very poor.

Mobilization rates of amino acids, fatty acids and carbohydrates during experimental diet induced kwashiorkor and obese conditions in rats.

Author: Mutwiri, Faith Ruguru Makena

Awarding University: University of Nairobi, Kenya

Level : MSc

Year: 1993

Holding Libraries: University of Nairobi Jomo Kenyatta Memorial Library ;

Subject Terms: Metabolism ; Research ; Biochemistry ;

Abstract:

Rats have been used extensively as animal models for the study of metabolic disorders such as in obesity and kwashiorkor. Previous studies using animal models have revealed that there are certain disorders in energy metabolism which are associated with obesity and kwashiorkor syndromes. This study was designed to explore further these metabolic defects by following the changes in activities of key regulatory enzymes involved in the energy generation pathways. Obesity and kwashiorkor are malnutrition states brought about by taking in of diets which have inadequate amounts or wrong proportions of certain nutrients. Kwashiorkor develops when the body is deprived of proteins but supplied with enough energy whereas obesity develops as a result of taking in more energy in the food than is expended in the activities of daily life. Obesity and Kwashiorkor syndromes were induced in 21 day old weanling rats by feeding them on high calorie, high protein diet and high calorie low protein diet respectively. The diets had enough vitamins and minerals. The control rats were fed on a balanced diet of commercial rat pellets. All groups were allowed free access to food and water for 3 weeks and their weight was taken weekly. The activities of the key regulatory enzymes involved in carbohydrate, fatty acid and amino acid metabolism were measured in the liver, the heart and in the leg muscle homogenates. The levels of some metabolites namely lactate, pyruvate glucose and glycogen were also determined in the homogenates. The effects of malnutrition states (obesity and kwashiorkor) on mitochondria function was also studied. The results of this study indicated that the rats fed on a high calorie high protein diet attained greater weight (133 %) than the control rats while those on low protein diet were characterized by general body wasting and loss of 28 % of the weight. These two conditions were characteristic of obese and Kwashiorkor syndrome respectively. Results on enzyme activities showed an increase in the activities of phosphofructokinase, pyruvate kinase, hexokinase and 3 hydroxy-acyl CoA dehydrogenase in the Kwashiorkor rats when compared to the control rats . . This indicated a marked elevation of the glycolytic flux and fatty acid breakdown leading to energy generation during Kwashiorkor states. In the obese rats there was a marked increase in the activities of glucose-6-phosphate dehydrogenase, citrate lyase, malate dehydrogenase, citrate synthase and isocitrate dehydrogenase relative to the control. These results suggest increased energy production and storage in the obese rats. The results on enzymes related to amino acid metabolism indicated that the activity of glutamate oxaloacetate transaminase (GOT) was elevated in all the tissues of the obese and Kwashiorkor rats. While that of glutamate pyruvate transaminase (GPT) was decreased in all the tissues of both the obese and Kwashiorkor rats. The levels of glucose were reduced the livers of obese and Kwashiorkor rats but there was a slight increase in the muscles of these animals. Pyruvate levels were notably less in the obese and Kwashiorkor rats indicating increased flux through glycolysis. The levels of glycogen were highest in the Kwashiorkor rats, followed by obese and least in the control rats. The respiratory control ratio of the mitochondria isolated from obese and Kwashiorkor rat liver was less than that of the control animals. These results indicate that the mitochondria from obese and Kwashiorkor rats are not as efficient in producing energy when compared to the control animals. Taken together the results indicated that: (i) The Kwashiorkor rats are able to make up for their inability to produce ATP from oxidative phosphorylation by accelerating the glycolytic flux and fatty acid breakdown. (ii) The metabolism in obese rats is diverted toward energy storage as evidenced by the increased fatty acid synthesis and elevated activities of the enzymes involved in the lipogen

Studies on the effect of ammonium sulphate and sodium nitrate on crassulacean acid metabolism (CAM) in Kalanche species.

Author: Makobe, Martha Namayi

Awarding University: University of Nairobi, Kenya

Level : MSc

Year: 1991

Holding Libraries: University of Nairobi Jomo Kenyatta Memorial Library ; University of Nairobi Chiromo Library ; University of Nairobi Upper Kabete Library ;

Subject Terms: Kalanche ; Crassulacean acid metabolism ;

Abstract:

ABSTRACT NOT AVAILABLE

A study of energy balance in children during and after acute measles

Author: Duggan, Maureen Brigid

Awarding University: University of London, England

Level : PhD

Year: 1985

Holding Libraries: University of Nairobi Medical Library ;

Subject Terms: Measles ; Children and youth ; Babies ; Nutrition ; Metabolism ; Growth disorders ;

Abstract:

Children eating poorly and suffering frequent infections do not achieve their genetic growth potential. The relative importance of infection and underfeeding in the causation of childhood malnutrition is still debated. The nutritional cost of infection was investigated by studying the energy balance during and after measles in 20 black children in hospital in Nairobi, Kenya. The energy content of a 24 hour collection of food, faeces and urine was determined by bomb calorimetry and the respiratory gaseous exchange was measured by the flow over method of indirect calorimetry. The levels of oxygen consumption (ROC) and metabolic rate (RMR) during resting metabolism i.e. >4 hours after food were similar during measles and after recovery; ROC = 8.8?0.34 and 9.27?0.32 mls/kg.min M?SE, RMR = 10.7?0.58 and 11.3?0.36 kJ/kg.hour M?SE respectively. Post prandial oxygen consumption and MR were significantly higher in the control study than the mean resting levels; PPOC = 10.34tO.46 mls/kg.min and PPMR = 12.8?0.58 kJ/kg.hour (p <0.02 and p <0.01 respectively). No post prandial increase in metabolism was seen during measles. The respiratory quotient (RQ) in healthy children eating a mainly carbohydrate diet in the control study, remained high throughout the 24 hours; RRQ= 0.97?0.03 and PPRQ = 0.93?0.03. The RQ was significantly lower during measles (p <0.01; RRQ = 0.83?0.02 and PPRQ = 0.80?0.03) and the gross energy intake was significantly (p <0.001) reduced (94.l?18.5 kJ/kg.24 hours) in comparison with the control intake (374?29.6 kJ/kg.24 hours). Metabolisable energy (ME) represented 75% of gross energy intake during measles and 87% during the 'control study. The significant linear relationship between apparent energy balance B, (estimated as B ME-RMR) is given by the equation B 0.952 ME - 253, r 0.973. Thus the ME at zero balance 265.8 kJ/kg.24 hours. The shortfall in available dietary energy during measles, and absence of the post prandial biosynthesis which is associated with an enhanced PPMR are strong indications that growth is interrupted during measles. The persistently high RQ during the control study suggests that lipogenesis from carbohydrate continues throughout the 24 hours. The sustained level of RMR in the absence of biosynthesis in the infection study, suggests that the truly basal metabolism may be enhanced during acute measles. The value for MEat zero apparent energy balance, 266 kJ/kg.24 hours, is proposed as an estimate of the maintenance energy requirement MER, based on a unique, if fortuitous, underfeeding study in children.

Some aspects of the regulation of proline metabolism in the flight muscle of the Tsetse fly Glossina morsitans.

Author: Olembo, Norah Khadzini

Awarding University: University of Nairobi, Kenya

Level : PhD

Year: 1980

Holding Libraries: University of Nairobi Medical Library ; University of Nairobi Chiromo Library ;

Subject Terms: Insects ; Glossina ; Entomology ; Glossina morsitans ; Metabolism ;

Abstract:

The purpose of this study was to investigate and extend knowledge of the oxidation of proline in the flight muscle of the tsetse fly Glossina morsitans. In various aspects of this work, metabolic comparison has been made with a more typical dipteran, the flesh fly Sarcophaga tibialis. Enzyme activities were assayed in the tsetse fly and compared to those of the flesh fly inorder to gain further insight into title importance of proline oxidation in these insects. NAO-linked malic enzyme was particularly active in tsetse fly muscle and for comparison, this enzyme was also measured in the flight muscle of a variety of other insect species. The enzyme was purified from tsetse fly thoraces and studied in detail, and the factors controlling its activity in vitro were investigated. Changes in metabolite levels in the thorax during early stages of flight were studied both in the tsetse fly and in the flesh fly, inorder to gain some insight into the factors that control their flight muscle metabolism in vivo.

A study of true blood sugar value in neonates.

Author: Mugo, Joseph Ndungu

Awarding University: University of Nairobi, Kenya

Level : MMed

Year: 1976

Holding Libraries: University of Nairobi Medical Library ;

Subject Terms: Babies ; Blood ; Glucose ; Metabolism ;

Abstract:

ABSTRACT NOT AVAILABLE

Some effects of halothane and carbon tetrachloride on hepatic metabolism

Author: Ahmad, Z

Awarding University: University of Nairobi, Kenya

Level : PhD

Year: 1975

Holding Libraries: University of Nairobi Medical Library ;

Subject Terms: Liver ; Metabolism ; Halothane ; Carbon tetrachloride ;

Abstract:

ABSTRACT NOT AVAILABLE