Showing papers by "University of Nairobi published in 1991"

Immunization of mice and baboons with the recombinant Sm28GST affects both worm viability and fecundity after experimental infection with Schistosoma mansoni.

Abstract: A member of the glutathione S-transferase family, Sm28GST has previously demonstrated a good ability to protect rodents against experimental infection with Schistosoma mansoni. In order to evaluate its efficacy in a model closer to man, two different protocols of immunization with recombinant Sm28GST were tested on baboons in a large-scale trial. Three injections in the presence of aluminium hydroxide as adjuvant resulted in a significant 38% reduction in the adult worm burden together with a trend for a lower percentage of inflammatory tissue in the liver. Individual levels of protection, ranging from 0 to 80%, underlined the heterogeneity of the immune response to this purified molecule in outbred primates. On the other hand, two injections of Sm28GST in the presence of aluminium hydroxide and Bordetella pertussis reduced female schistosome fecundity by 33%, with a more pronounced effect (66%) on faecal egg output; there was also a trend, in this protocol, for decrease of the mean granuloma surface in the liver. Individual anti-Sm28GST IgG antibodies were apparently unrelated to levels of immunity, but there was partial evidence that cytophilic IgE might play a role in the immune mechanisms affecting worm viability, but not fecundity. In the mouse model, Sm28GST vaccination resulted in a lower hatching ability of tissue eggs recovered from immunized mice whereas passive transfer of specific anti-Sm28GST T-lymphocytes, one day before infection, significantly reduced the number of eggs in the liver of mice. We propose that different protocols of immunization with a recombinant molecule can impede Schistosoma mansoni worm viability and fecundity, but can also affect miracidium physiology, with important consequences for disease transmission and granuloma-derived pathology.

The importance of core groups in the epidemiology and control of HIV-1 infection.

Abstract: In Africa HIV transmission occurs mainly through heterosexual intercourse. High-frequency transmitter core groups are key to the epidemiology of HIV-1 and STD on the continent. The rapid growth of the HIV-1 epidemic in Africa appears to have resulted in part from social and economic factors which result in individuals frequent engagement in sexual intercourse with members of HIV-infected core groups. Understanding the importance of core groups in HIV-1 transmission is therefore key to developing more effective programs for the control of HIV-1. Sections explore the core groups concept and the sexual transmission of infection social and economic forces creating core groups in Africa the interaction of STD and HIV-1 in core groups the effect of STD on HIV-1 disease progression in core groups in accelerating the HIV-1 epidemic the role of core group interventions in control programs balancing disease control with the potential for victimization and research needs.

Controlling HIV in Africa: effectiveness and cost of an intervention in a high-frequency STD transmitter core group.

Abstract: Since 1985 a population of over 1000 predominantly HIV-positive female prostitutes residing in a low-income area of Nairobi has been enrolled in a sexually transmitted disease (STD)/HIV control program. The major components of the program include the diagnosis and treatment of conventional STDs and the promotion of condom use to prevent HIV transmission and other sexually transmitted infections. Using estimates of numbers of HIV-seropositive prostitutes numbers of sexual contacts susceptibility of clients to HIV HIV transmission efficiency rates of condom use and the basic reproductive rate of HIV infection in Kenya the authors estimate that the program is responsible for preventing between 6000-10000 new cases of HIV infection/year among clients and contacts of clients. The total annual operating cost of the program is approximately US$77000 or between US$8.00-$12.00 for each case of HIV infection prevented. Programs to reduce the transmission of HIV and other sexually transmitted infections which are targeted at high frequency STD transmitters such as prostitutes can be effective and relatively inexpensive to undertake. More such programs should be developed and evaluated in different settings. (authors)

Resource base, parity, and reproductive condition affect females' feeding time and nutrient intake within and between groups of a baboon population.

Abstract: We examined within- and between-group differences in aspects of feeding and nutrient intake among adult females of a single population of baboons (Papio cynocephalus) in Amboseli National Park, Kenya. Differences in time spent feeding, daily energy and protein intake and feeding efficiency (nutrient intake per minute spent feeding) reflected differences in resource base, reproductive condition and parity. Baboons that partially fed from a lodge garbage dump spent less than half the time feeding than those that were feeding totally in the wild. During this greatly reduced feeding time, the garbage-feeding group had a similar daily energy intake and only a slightly lower daily protein intake relative to wild-feeding baboons. Consequently, the feeding efficiency of the semi-provisioned baboons was appreciably higher than that of the non-provisioned baboons. For the totally wild-feeding baboons, samples were large enough to permit analyses of feeding time and nutrient intake during different reproductive states and parity. Females spent more time feeding and had higher daily energy and protein intake when they were pregnant or lactating than when they were sexually cycling. Nulliparous females spent more time feeding than their multiparous counterparts. The daily energy intake of nulliparous females was higher than that of their multiparous counterparts, but their daily protein intakes did not differ significantly. Pregnant or lactating and nulliparous females had higher feeding efficiency than their sexually cycling and multiparous counterparts. The two nulliparous females in the garbage-feeding group spent more time feeding but did not take in more energy or protein per day than their multiparous counterparts.

Weight and age in wild olive baboons.

Abstract: Data on weight, toothwear, cape length, testes size, canine size, and age from wild olive baboons are presented in order to consider the nature of the growth curve, the differences between males and females in a sexually dimorphic species, and the effect of nutrition on growth parameters. Longitudinal and cross-sectional data on weight and age in three troops that lived under a variety of ecological circumstances showed a good fit to the von Bertalanffy growth equation. Male and female baboons have different growth constants (K) and different asymptotic weights and ages resulting in the observed baboon sexual dimorphism. Within sexes, growth constants and asymptotic weights varied between troops in the same year and for the same troop in different years. Improvements in nutrition increased growth rate and final weight and decreased age at asymptote in both naturally foraging and in food-enhanced wild groups. Testes and cape length follow the same growth pattern and have the same asymptotic age as body mass among naturally foraging males. Canine growth is different with full size achieved nearly 2 years earlier. Toothwear is an accurate relative age indicator for immature and adult females and for immature males but not for adult males because of the role that large canines play in occlusion and wear. The data suggest that creating a dichotomy between captive and wild primates is overly simplistic since conditions for growth in the wild can overlap those of captivity, not just for food enhanced individuals but also among naturally foraging troops. The nutritional perspective on primate growth exposes inherent problems in our present system of primate age classification which have serious implications for the use of age classes in behavioral analyses.

Prediction of cognitive competence in Kenyan children from Toddler nutrition, family characteristics and abilities.

Abstract: This study explored the extent to which cognitive competence in 5-yr old Kenyan children was associated with earlier nutritional factors, family conditions and toddler characteristics Food intake during the 18th-30th mths and physical stature at 30 mths were associated with cognitive skills at 5 yrs Measures of family background, abilities of the child as a toddler and current schooling were also associated with cognitive abilities at 5 yrs These variables influenced development independently, so that later cognitive competence was best predicted by a combination of earlier nutritional, family and toddler characteristics

Mouthbreathing, lip seal and upper lip coverage and their relationship with gingival inflammation in 11-14 year-old schoolchildren.

Abstract: The gingival health of 201 schoolchildren aged 11-14 years was assessed at 6 sites on all the incisor and first molar teeth by recording separately the presence or absence of redness and bleeding on probing. Crowding of the incisor teeth was recorded as labio-lingual displacement and mesio-distal overlap. A 2nd examiner recorded the presence or absence of plaque at these sites and assessed mouthbreathing, lipseal and upper lip coverage of the maxillary incisors. Mouthbreathing, increased lip separation and decreased upper lip coverage at rest were all associated with higher levels of plaque and gingival inflammation. Multivariate analysis indicated that this association was statistically significant for mouthbreathing and lip coverage but increased lip separation was not independently related to plaque and gingivitis. The relationship of mouthbreathing and decreased upper lip coverage with gingivitis was most evident in the upper anterior segment and was still evident after covariate analysis to take account of variations due to gender, overcrowding and amount of plaque. However, allowance for these factors also suggested that the influence of mouthbreathing was restricted to palatal sites, whereas lip coverage influenced gingival inflammation at both palatal and labial sites.

Release and survival of Echinococcus eggs in different environments in Turkana, and their possible impact on the incidence of hydatidosis in man and livestock.

Abstract: In Turkana, Kenya, a prevalence of hydatidosis of nearly 10% has been recorded among the pastoralists yet their livestock have a much lower prevalence of the disease. The present study investigated the release from dogs and subsequent survival of Echinococcus eggs in Turkana huts, water-holes and in the semi-arid environment. The results were compared with the survival of eggs of Taenia hydatigena and T. saginata. The study was repeated under the cooler and moister conditons found in Maasailand where livestock have a greater incidence of hydatid disease than in Turkana but where the incidence in man is ten times lower. The average number of Echinococcus eggs per proglottid is 823. Nine percent of these remain in proglottids 15 minutes after release from a dog and the released eggs lose their viability in less than two, 48 and 300 hours in the sun, huts and water in Turkana respectively; the major influencing factor being temperature. The greater survival of eggs in the houses, coupled with the fact that dogs congregate for most of the day in the small houses facilitating a close man:dog contact, provide ideal conditions for the trasmission of the parasite to man. The hostile environmental conditions and lack of contact between dogs and livestock contributes to the lower infection rate in livestock. Conversely in Maasailand, Echinococcus eggs survive in the environment for longer than three weeks and in addition, dogs are used for herding. This partly explains the higher infection rate among Maasai livestock but the low human infection rate remains arcane and requires further study. The rapid mortality of the majority of Echinococcus eggs in Turkana suggests that control measures aimed at dog control and a decreased man:dog contact should have a profound effect on the incidence of the disease in an area intrinsically unsuitable for the parasites' survival.

Food plants of the Luo of Siaya district, Kenya

Abstract: Plants used for food by the Luo-speaking people of Siaya District, Kenya, were surveyed as part of a comprehensive ethnobotanical study. Fifty-two crops were observed under cultivation in the district; 69 species are gathered from the wild. Wild fruits, underground portions, leaves, and fungal fruiting bodies are probably important in Siaya as dietary supplements. These non-cultivated resources, particularly important in the driest areas of the district, warrant evaluation for their role as a buffer against periods of food shortage.

Long distance truck drivers. 2: Knowledge and attitudes concerning sexually transmitted diseases and sexual behaviour.

Abstract: 337 truck drivers aged 14-61 years with mean age 31 travelling from Mombasa to eastern and central African destinations were interviewed to assess their knowledge on AIDS and sex practices. 99% had heard of AIDS through the mass media and from friends and 87% described AIDS as a sexually transmitted disease which causes body wasting and death. 61% claimed to have visited prostitutes and 76% were aware that condom use can prevent AIDS transmission and infection yet only 32% claimed to have ever used condoms. Less than 1% claimed to always use condoms with sex partners. Of 188 respondents 18% stated that they did not use condoms because they did not have sex with prostitutes 18% saw no reason to use them and 18% cited condom unavailability. A large gulf therefore exists between sex/AIDS acquisition and transmission. Condom use should be promoted in this and similar groups of men and their prostitute contacts with attention to develop motivational strategies complementary to education interventions.

Extrusion Cooking of Corn/Soybean Mix in Presence of Thermostable α‐Amylase

Abstract: A fractional factorial experiment of a 34 second order orthogonal design was used to study properties of extrusion processed corn/soybean (70/30%, w/w) mixtures in presence of thermostable α-amylase. The viscosity of gruels made from extrudates of corn/soybean mixtures with no added α-amylase was more than 1000-fold higher than that of products extruded with added enzyme. Changes in viscosity and water solubility and absorption indices of slurries from extrudates made under different conditions, indicated enzymatic starch hydrolysis was increased in the extruder when a-amylase was included. The results should be useful in selecting extrusion conditions to yield low viscosity-high nutrient density gruels from extruded products.

Interspecific hybrids and possible phylogenetic relations in grain amaranths

Abstract: Phylogenetic relations among the three species in grain amaranth need investigation to provide information for breeding experiments germplasm conservation efforts, and decision on evolutionary patterns in the grain types. Hybrid development from crosses between species was studied to find out genetic relationship between them. Interspecific crosses were made among Amaranthus hypochondriacus, A. caudatus and A. cruentus in the glasshouse. The F1 plants were relatively easy to obtain but had low pollen fertility (10.3–15.1%) and low seed set. A few of these hybrids did not produce seeds. Only a few F1 seeds obtained in crosses between A. cruentus and A. caudatus. All the F1 plants from these crosses died at the seedling stage. Crosses between A. cruentus and A. hypochondriacus produced few seeds. Most of the F1 plants obtained from the seeds died at the seedling stage with only four plants growing to maturity but were sterile. Based on hybrid development, it was suggested that A. hypochondriacus and A. caudatus were genetically closer than the other two combinations of species studied. A. cruentus seemed to be genetically closer to A. hypochondriacus than it was to A. caudatus.

Lead contamination in street soils of Nairobi City and Mombasa Island, Kenya.

Abstract: The advent of modern industrialization and, in particular, the motor vehicle has witnessed dramatic increases in lead usage both as a component of lead-acid storage battery and from 1923 as organic lead alkyl anti-knock additive in petroleum. Several workers have established a correlation between increasing lead concentration in roadside soils and vehicular traffic density. Although researchers studied the heavy metal content in Lake Victoria sediments, no urban roadside soils were investigated. Since lead is used as a petrol additive in Kenya, it is necessary to document the extent and magnitude of lead contamination of roadside soils in inland and coastal urban environments and evaluate its environmental implications.

A morphometric study of the lungs of different sized bats: correlations between structure and function of the chiropteran lung.

Abstract: 1. The lungs of four species of bats, Phyllostomus hastatus (PH, mean body mass, 98 g), Pteropus lylei (PL, 456 g), Pteropus alecto (PA, 667 g), and Pteropus poliocephalus (PP, 928 g) were analysed by morphometric methods. These data increase fivefold the range of body masses for which bat lung data are available, and allow more representative allometric equations to be formulated for bats. 2. Lung volume ranged from 4.9 cm3 for PH to 39 cm3 for PP. The volume density of the lung parenchyma (i.e. the volume proportion of the parenchyma in the lung) ranged from 94% in PP to 89% in PH. Of the components of the parenchyma, the alveoli composed 89% and the blood capillaries about 5%. 3. The surface area of the alveoli exceeded that of the blood-gas (tissue) barrier and that of the capillary endothelium whereas the surface area of the red blood cells as well as that of the capillary endothelium was greater than that of the tissue barrier. PH had the thinnest tissue barrier (0.1204 microns) and PP had the thickest (0.3033 microns). 4. The body mass specific volume of the lung, that of the volume of pulmonary capillary blood, the surface area of the blood-gas (tissue) barrier, the diffusing capacity of the tissue barrier, and the total morphometric pulmonary diffusing capacity in PH all substantially exceeded the corresponding values of the pteropid species (i.e. PL, PA and PP). This conforms with the smaller body mass and hence higher unit mass oxygen consumption of PH, a feature reflected in the functionally superior gas exchange performance of its lungs. 5. Morphometrically, the lungs of different species of bats exhibit remarkable differences which cannot always be correlated with body mass, mode of flight and phylogeny. Conclusive explanations of these pulmonary structural disparities in different species of bats must await additional physiological and flight biomechanical studies. 6. While the slope, the scaling factor (b), of the allometric equation fitted to bat lung volume data (b = 0.82) exceeds the value for flight VO2max (b = 0.70), those for the surface area of the blood-gas (tissue) barrier (b = 0.74), the pulmonary capillary blood volume (b = 0.74), and the total morphometric lung diffusing capacity for oxygen (b = 0.69) all correspond closely to the VO2max value. 7. Allometric comparisons of the morphometric pulmonary parameters of bats, birds and non-flying mammals reveal that superiority of the bat lung over that of the non-flying mammal.(ABSTRACT TRUNCATED AT 400 WORDS)

Condom use prevents genital ulcers in women working as prostitutes. Influence of human immunodeficiency virus infection.

Abstract: Control of genital ulcer disease (GUD) is a proposed intervention to slow the dissemination of human immunodeficiency virus (HIV) infection. Programs for the control of sexually transmitted diseases (STD) should focus on groups of high-frequency transmitters, such as prostitutes and their clientele. This study illustrates the interaction between the prevalence of chancroid, use of barrier prophylaxis against STDs, and HIV infection in a population of female prostitutes in Nairobi. Four hundred and twenty three women were evaluated. Despite the increased use of condoms, the prevalence of genital ulcers remained constant between 1986-87 and 1987-88. Genital ulcer disease was simultaneously associated with HIV infection (adjusted odds ratio: 3.7, P less than .01) whereas it was independently and inversely associated with more consistent condom use (P less than .01). The authors conclude that genital ulcer disease can be controlled in these populations but concurrent HIV infection increases the difficulty of this intervention.

Intake of fluoride and excretion in mothers' milk in a high fluoride (9 ppm) area in Kenya.

Abstract: In 27 nursing mothers a study was made on breast milk fluoride (F) levels and the 24-h intake of F through foods and beverages. The daily F intake averaged 22.1 mg (range 9.5-37.2 mg); cooked food contributed 11.7 mg, water 4.5 mg and tea 5.8 mg. The breast milk F concentration averaged 0.033 mg/l (range 0.011-0.073 mg/l). No significant correlation could be established between the milk F level and the intake of F. The milk F level was, however, correlated positively to mothers' age and negatively to mothers' weight. It is concluded that the milk fluoride level was only moderately increased by the high intake of F, and that the children's intake of F through mothers' milk was negligible compared to the very high F intake through complementary foods and beverages.

The effects of experimental Trypanosoma (trypanozoon) (brucei) evansi infection on the fertility of male goats

Abstract: The effects on the fertility of small East African male goats of intravenous infection with Trypanosoma (t) (b) evansi were studied. Six infected bucks developed erratic, low but persistent parasitaemia, the packed cell volume dropped gradually but significantly (p<0.001) and they became emanciated. Half of these bucks developed clinical orchitis. Two bucks died of the disease during the experiment.

Oral hygiene practices and periodontal health in primary school children in Nairobi, Kenya.

Abstract: The purpose of this study was to obtain data on the oral hygiene practices, oral hygiene status, and periodontal health among primary school children in Nairobi. The study group consisted of 513 children, 262 aged 6-8 years and 251 aged 13-15 years. The children were from 6 schools randomly selected among the 154 public primary schools in the city. The clinical examination was performed in a room with natural daylight, using the WHO (1980) criteria. Although most of the children reported brushing habits, 75% of the index tooth surfaces in the younger and 55% in the older age group had visible plaque. In both age groups about 25% of the index sites had gingivitis. Moderate amounts of calculus were recorded among the older children. Only two children had periodontal pockets greater than or equal to 4 mm. There was no statistically significant difference (p greater than 0.05) between males and females recorded with plaque and gingivitis in the younger age group. In the older group, however, a significantly higher proportion of males (p less than 0.05) were recorded with plaque and gingivitis. The oral hygiene practices and oral hygiene status were poorer among children from low than from high socioeconomic status. Provision of dental health education for children in Nairobi is recommended.

Essential oils of Kenyan Lippia species. Part III

Abstract: Essential oils from six Lippia species (fam. Verbenaceae), namely Lippia javanica (Burm f.) Spreng., L. dauensis (Chiov.) Chiov., L. carviodora Meikle, L. carviodora var. minor Meikle, L. grandifolia Mart & Schau., and L. wilmsii H. H. W. Pearson, have been analysed by GC and GO-MS. Myrcenone, cis- and trans- ocimenone have been found to be the major constituents of essential oil of L. Javanica. β-Ocimene, cis-tagetone and 2-methyl-6-methylene oct-7-en-4-one are major compounds of L. dauensis oil. L. carviodora var. minor oil consists primarily of sesquiterpene hydrocarbons, β-cubenene being the major constituent.

The prevalence and nutritional value of some Kenyan indigenous leafy vegetables from three locations of Machakos district

Abstract: A survey was carried out to determine the locally available leafy vegetables in three locations of Machakos District, Kenya. The most common vegetables were analyzed for vitamin C, beta‐carotene calcium, iron and oxalate. Consumption of wild and semi‐wild leafy vegetables was found to be common in the three locations especially during the dry seasons. Results of laboratory analyses revealed high levels of beta‐carotene and vitamin C, and iron, and moderate levels of the mineral calcium, in the majority of the vegetables. Most vegetables were found to satisfy more than 100% of the daily requirements for vitamins A and C and more than 50% of the mineral calcium for an adult male. Three of the vegetable species analyzed had high levels of oxalate.

Antimicrobial resistance of enteropathogenic Escherichia coli strains from a nosocomial outbreak in Kenya.

Abstract: The majority of the 78 enteropathogenic (EPEC) and the 151 non-EPEC Escherichia coli strains isolated from preterm neonates during an outbreak of gastroenteritis in a hospital in Nairobi, Kenya, were resistant to trimethoprim-sulfamethoxaxole, chloramphenicol, oxytetracycline and ampicillin, but only a few strains were resistant to cefazolin, cefamandole, cefotaxime, amikacin and nalidixic acid. Fourteen different antimicrobial resistance patterns were observed in the 229 strains of E. coli analysed. Eighty-two percent of the EPEC strains belonged to two resistance pattern compared with 79% of non-EPEC strains which exhibited three resistance patterns. There was no consistent relationship between plasmid profile group and antimicrobial resistance pattern, although one resistance pattern was more frequently observed in EAF-positive strains belonging to the dominant plasmid profile group. Nine percent of the EPEC strains were resistant to gentamicin compared to 37% in the non-EPEC group. No correlation was observed between administration of gentamicin and percentage of resistant strains isolated. None of the nine neonates receiving gentamicin died during the outbreak. Gentamicin resistance was observed in E. coli strains from six out of these nine neonates. Five out of fourteen neonates who received other antimicrobials, or no antibiotic treatment at all, died.

Fluorosis of deciduous teeth and first permanent molars in a rural Kenyan community.

Abstract: The severity and distribution of fluorosis in the deciduous dentition of 76 children in a low-income community near Nairobi were studied Seventeen children comprised a low-F (fluoride) group (water less than 07 ppm F) and 59 a high-F group (water approximately 9 ppm F) The high-F group had scores greater than or equal to 5 in the Thylstrup & Fejerskov classification system for 29% of the deciduous tooth surfaces, compared with 7% in the low-F group Comparison between the scores of the second deciduous and the first permanent molars showed no significant difference in the high-F group (p greater than 0001), whereas the deciduous molar was significantly less severely affected in the low-F group (p less than 0001) The deciduous molars of the two groups differed significantly (p less than 0002), but not the permanent molars (p greater than 010) Early introduction of tea might have been a major contributor to the distributions of fluorosis, particularly in the low-F group

A morphometric analysis of chloride cells in the gills of the teleosts Oreochromis alcalicus and Oreochromis niloticus and a description of presumptive urea-excreting cells in O. alcalicus.

Abstract: The gills of Oreochromis alcalicus, a hyperosmotic and low pH adapted teleost, and Oreochromis niloticus, a freshwater closely related fish have been investigated by transmission electron microscopy and a morphometric analysis of, particularly, the chloride cells and their primary organelles, the mitochondria and the tubulo-vesicular system carried out. Oreochromis alcalicus had a fourfold greater number of chloride cells than O. niloticus and the chloride cells had more mitochondria and a more profuse tubulo-vesicular matrix. The ultrastructural features of the chloride cells of Oreochromis alcalicus were interpreted as adaptations for the severe ecosystem that the species inhabits. Putative urea excreting cells unique to the gills of Oreochromis alcalicus are described.

Social Organization, Resource Management, and Child Nutrition in the Taita Hills, Kenya

Abstract: A comparative and longitudinal ecological analysis is used to explore agricultural sources of variation in child nutritional status in the Taita Hills, Kenya. National policies, formal institutions, the natural environment, and the local-level social organization of agricultural resource access define the agrarian context within which distinct production strategies emerge. The effects of alternative production choices on child nutrition are neither consistent nor unidimensional, arguing for a rethinking of conventional approaches to food policy decision making.

Oxamniquine pharmacokinetics in healthy Kenyan African volunteers.

Abstract: Oxamniquine pharmacokinetics were studied following oral administration of 750, 1000 mg or 1250 mg (equivalent to approximately 15 mg/kg) to five healthy Kenyan African volunteers. Peak plasma concentrations ranging between 1 and 4.3 mg/1 were achieved 1 to 4 h after dosing. The estimated mean elimination half-life (t1/2) was 2.2 h. Despite the limited number of subjects in the study, it is concluded that the pharmacokinetics of oxamniquine in healthy Kenyan Africans do not markedly differ from those in Africans from other regions of the continent where previous studies have been reported.