Showing papers by "University of Nairobi published in 1983"
TL;DR: When the angle of the IMF to the earth sun line is 15 deg or less, the occurrence rate of dayside Pc 3,4 pulsations in 7-8 times the average at L values of 2.4-2.8.
Abstract: When the angle of the IMF to the earth sun line is 15 deg or less, the occurrence rate of dayside Pc 3,4 pulsations in 7-8 times the average at L values of 2.4-2.8, and 2.2-3.5 times the average at L of 4-4.3. These waves disappear when the IMF is nearly at right angles to the sun-earth line. Such observations are consistent with a source originating in the waves upstream of the subsolar bow shock, which are transported by convection to the magnetopause. There, they couple to oscillations of magnetospheric field lines. Because the magnetospheric plasma's index of refraction decreases with radial distance except at the plasmapause, inwardly propagating waves should be refracted away from the radial direction. To reach low L values, the waves should therefore couple near the stagnation point and propagate nearly radially inwards. The streamline geometry and its connection to the foreshock region is illustrated for various IMF orientations, using a simple approximation to the magnetosheath flow field.
145 citations
TL;DR: Of 300 men in Nairobi, Kenya, with culture-proven chancroid, 57% had acquired infection from prostitutes, and no evidence of transmission of H ducreyi by women without clinical Chancroid was detected.
97 citations
TL;DR: Results support the hypothesis that AFB may play an important role in the etiology of human liver cancer and interaction between the ultimate carcinogenic form of AFB and cellular nucleic acids in vivo.
Abstract: Food samples collected in Murang'a district, Kenya are known to be contaminated with a mycotoxin, aflatoxin B1 (AFB), and a positive correlation exists between the dietary intake of AFB and the incidence of liver cancer. When urine samples collected in this district were analyzed for the presence of 2,3-dihydro-2-(7'-guanyl)-3-hydroxyaflatoxin B1 (AFB-GuaI) by h.p.l.c., 6 of 81 samples had a detectable level of a compound whose fluorescence spectrum was identical to chemically synthesized AFB-GuaI as confirmed by photoncounting fluorescence spectrophotometry. These results are an indication of interaction between the ultimate carcinogenic form of AFB and cellular nucleic acids in vivo and further support the hypothesis that AFB may play an important role in the etiology of human liver cancer.
73 citations
TL;DR: Most of the Kenyan camel stocks were found to be either identical or closely similar to T (T) evansi stocks from elsewhere and were therefore designated T ( tsetse transmissible), and four other Kenyan stocks were electrophoretically distinct, and one of them showed marked pleomorphism in rat blood.
70 citations
TL;DR: In the colobus monkeys the basal metabolic rate (BMR) was considerably lower than in the Sykes monkeys: 85% vs 113% of the value predicted from body mass.
54 citations
TL;DR: Yields of testosterone and 11-ketotestosterone glucuronides while showing a peak at 22 degrees declined much more slowly at higher temperatures than did those of the free steroids, and levels of all steroids were below the limits of detection.
53 citations
TL;DR: There appears to be little or no clinical toxoplasmosis in Kenya but serological studies indicate a widespread distribution of the parasite in the human population.
Abstract: 322 samples of sera from blood donors in four areas of Kenya were screened for Toxoplasma gondii antibodies by haemagglutination and 54% proved positive. 299 of these were also tested by dye test and 42% were positive, with 5·9% showing high titres indicating possible active infection. Parasitological examination of the buffy coat from donors was also carried out on 100 samples but no Toxoplasma parasites were seen in spite of high antibody incidence. There appears to be little or no clinical toxoplasmosis in Kenya but serological studies indicate a widespread distribution of the parasite in the human population.
50 citations
TL;DR: While the development of flehmen was characterized by a bimodal trend, mounting activity was pronounced only during the first year of life; it declined at the age of weaning and remained at low levels during the second and third years of life.
45 citations
TL;DR: The buffalo, oryx and gerenuk were somewhat more unique in gastrointestinal composition than were other species of wild ruminants, and were deserving of special consideration.
43 citations
TL;DR: Small-intestinal function was studied in 10 patients with visceral leishmaniasis and there was a significant improvement in absorption of vitamin A and d-xylose, and biopsy specimens became normal.
41 citations
TL;DR: The effects of different management systems, traditional nomadic vs. commercial ranching, on growth, fertility and early mortality, as well as the differences in the genetic potential of two types of indigenous camels are described.
Abstract: Initial results from an ongoing study of the productivity in three herds of camels are presented. The effects of different management systems, traditional nomadic vs. commercial ranching, on growth, fertility and early mortality are described as well as the differences in the genetic potential of two types of indigenous camels.
TL;DR: It is suggested that increased ventilation of the suprabranchial chambers and greater oxygen extraction across the gills obviates the need for modifications in these parameters.
Abstract: Specimens of the African air-breathing catfish Clarias mossambicus were acclimated to either aerated (PwO2 15.3 KPa) or hypoxic (PwO2 2.4KPa) water for up to 27 days at 20 °C. Routine respiration rate for fish acclimated to aerated water was 85.7 mlO2 (kgbodyweight)−1 h−1. Gas exchange across the suprabranchial chambers accounted for 25% of the total. In aerated water the interval between air-breaths varied from 1.4 to 30.6 min. On acute exposure to hypoxia air-breathing frequency was unaltered (6.3 h−1) although aerial respiration rate increased by 70%. This suggests that ventilation of the suprabranchial chambers is variable and that air-breathing frequency is a poor measure of air-breathing effort. Total respiration decreased by 46% on acute exposure to hypoxia (PwO2 2.4 KPa), reflecting a reduction in routine activity. Following acclimation to hypoxia, airbreathing frequency (8.1 h−1) was higher and total routine respiration rate increased from 46.3 to 67.8 mlO2 kg−1h−1. The increased oxygen consumption with hypoxia acclimation was largely the result of an increase in aquatic respiration from 10.4 to 27.5 mlO2kg−1h−1 Measurements were made of mitochondrial volume densities [Vv(mt,f)] and capillary supply to fast and slow myotomal muscles. The fraction of fibre volume occupied by mitochondria was 15 percnt; for slow and 2.5% for fast muscles. Values for [Vv(mt,f)] obtained for fish slow fibres are much higher than for homologous muscles in birds and mammals and show a good correlation with capillary density [NA(c,f)]. Hypoxia acclimation did not result in changes in either muscle Vv(mt,f) or NA(c,f). It is suggested that increased ventilation of the suprabranchial chambers and greater oxygen extraction across the gills obviates the need for modifications in these parameters.
TL;DR: Chinese and African Euphorbiaceae plant extracts were shown to have a markedly enhancing effect on Epstein-Barr virus (EBV)-induced transformation of human lymphocytes, and the possible role as a co-factor of the plant extracts in the development of nasopharyngeal carcinoma (NPC) and African Burkitt's lymphoma (BL) is discussed.
TL;DR: An analysis of 470 cases of oculo-orbital tumors in Kenya finds retinoblastoma is reported in high numbers in African countries whereas uveal melanoma is extremely rare and squamous cell carcinoma occurs more frequently than in Caucasians.
TL;DR: In this article, the effect of phosphorus on nodulation, dry matter yield and dinitrogen fixation (as determined by the 15N technique) of bean plants (Phaseolus vulgaris) was evaluated in a field experiment at three growth stages.
Abstract: The effect of phosphorus on nodulation, dry matter yield and dinitrogen fixation (as determined by the 15N technique) of bean plants (Phaseolus vulgaris) was evaluated in a field experiment at three growth stages. Application of phosphorus increased nodule mass, dry matter yield, nitrogen yield and dinitrogen fixation at all the three stages (i.e. flowering, pod-filling, and physiological maturity) but the effects of phosphorus were more pronounced at the flowering and pod filling stages. The highest dinitrogen fixation was recorded within the pod filling stage where phosphorus was applied. The results clearly demonstrate that availability of phosphorus can be an important factor in symbiotic biological nitrogen fixation by beans. For these studies the best sampling time appears to be within the pod-filling stage. A biological approach in solving phosphorus problems in symbiotic biological nitrogen fixation by grain legumes is suggested.
TL;DR: Eighty Kenyan‘psychotic’patients were screened using the New Haven Schizophrenic Index (NHSI) and were all studied for hallucinations using standardised definitions, compared and contrasted with the very few similar observations made elsewhere.
Abstract: Eighty Kenyan‘psychotic’patients were screened using the New Haven Schizophrenic Index (NHSI) and were all studied for hallucinations using standardised definitions. Fifty-one of the patients were NHSI positive and the rest NHSI negative. Sixty-one percent of the NHSI positive had hallucinations in one or more modalities as compared with 31 % of the NHSI negative group. Of the NHSI positive 51 % had auditory hallucinations directly to the patient, 43 % had visual hallucinations and 25 % had olfactory hallucinations. These results are compared and contrasted with the very few similar observations made elsewhere.
TL;DR: Results are consistent with the original hypothesis which was based on structural data for the different hemoglobin chains, and show a large deletion in the DNA of the Kenya chromosome which includes the 3' section of the A gamma gene, the delta gene, and the 5'section of the beta gene.
Abstract: DNA was isolated from the white cells of a subject with the Hb S-Kenya-Gγ-HPFH condition, and digested with the restriction endo-nucleases Bgl II, Xba I, and Eco RI. The resulting fragments were identified by standard techniques using [32P] labelled probes which are specific for the second intervening sequences of the 6 gene and the y genes, respectively. A comparison with data for normal DNA indicated the presence of one additional fragment in each of the three digests, namely a 10.5 kb Bgl II fragment, a 7.8 kb Xba I fragment, and a 2.9 kb Eco RI fragment. These observations are believed to show a large (∼22.5 kb) deletion in the DNA of the Kenya chromosome which includes the 3′ section of the Aγ gene, the 6 gene, and the 5′ section of the β gene. These results are consistent with the original hypothesis which was based on structural data for the different hemoglobin chains.
TL;DR: Of those positive 73 % had First Rank Symptoms of schizophrenia as opposed to only 24 % in the group negative for schizophrenia, which is highly significant (P < 0.001).
Abstract: Eighty 'psychotic' patients admitted to Mathare Psychiatric Hospital, Nairobi, were screened using the New Haven Schizophrenic Index (NHSI). Fifty-one (64%) of these were positive and the rest negative. Of those positive 73% had First Rank Symptoms (FRS) of schizophrenia as opposed to only 24% in the group negative for schizophrenia. This difference is highly significant (P less than 0.001). The commonest individual FRS were thought echo, thought insertion, delusional mood and auditory hallucinations in third person. The frequency distribution of FRS had no relation to sex or age. These results are compared and contrasted with the findings of similar studies in various cultures.
TL;DR: A study into the economic effects of trypanosomiasis was carried out using three goat breeds at the south coast of Kenya using Samorin at the dose rate of 0.5 mg/kg body weight to evaluate the economic losses worked out by comparing the performance of the goat groups receiving Samor in on a monthly basis with that of goat groups not receiving any SamorIn.
Abstract: A study into the economic effects of trypanosomiasis was carried out using three goat breeds at the south coast of Kenya. The economic losses were worked out by comparing the performance of the goat groups receiving Samorin on a monthly basis with that of goat groups not receiving any Samorin. The losses were based on quantities of weight lost through deaths and that not produced as a result of the disease. The groups of goats were exposed to natural trypanosomal challenge.
TL;DR: Predation on larvae by the pied crow Corvus albus in some observation sites reduced larval numbers, and may have prevented NPV from rising to epizootic levels in such areas.
Abstract: Field observations were carried out on a natural outbreak of a nuclear polyhedrosis virus of the armyworm Spodoptera exempta. Records were kept in four study sites with varying larval density, vegetation cover, and climatic conditions. Biotic factors influencing disease outbreaks were also noted. Initial mortality was recorded 11 days after larval outbreak, and the highest mortality occurred 10 days later. The epizootic was highest in sites of high larval density, wide fluctuations of daily temperatures (range 16.2 °C), and high relative humidity. Rainfall was recorded in all disease outbreak sites. An acridid Acrotylus patruelis fed on larval cadavers in the field. Polyhedral inclusion bodies recovered from the gut of A. patruelis caused disease when fed to third instar S. exempta larvae in the laboratory. Predation on larvae by the pied crow Corvus albus in some observation sites reduced larval numbers, and may have prevented NPV from rising to epizootic levels in such areas. In sites of high polyhedrosis incidence, the disease led to larval population collapse in 3 weeks following disease outbreak.
TL;DR: In this paper, the authors found that rumen-reticulo (RR) fermentation rates in vitro were rapid, ranging from 524 in tropical Kenya to 395 in subtropical South West Africa (dikdik) and averaging 535 in Kenyan suni.
TL;DR: The observed biotransformation of cathinone to the less potent psychostimulant, d-norpseudoephedrine involves reduction of a ketone group to alcohol, a common metabolic pathway in humans.
TL;DR: The overall exposure rate of the virus rose from 10% in preschool children to 77% in adults and peaked twice, first after entering school and then after leaving school, and the transmission rate among the preschool children was much lower compared to the results of a rural study in Senegal.
Abstract: NOTE. The presence of hepatitis B surface antigen (HBsAg) was tested by passive HA (Hepatest(R); Wellcome Research, Triangle Park, NC); the presence of antibody to HBsAg (anti-HBs) and to hepatitis B core antigen (anti-HBc) was tested by RIAs (Abbott Laboratories, North Chicago, Ill). Overall, 7.5% of the study population constitute a potential reservoir for the spread of infection. Summary A serologic study of 655 black urban residents of Nairobi (a city in a nonmalarious region of Kenya) was carried out. There was no evidence of vertical transmission in 36 neonates tested, although 22 of them had the same antibody profile as their mothers. The overall exposure rate of the virus rose from 10% in preschool children to 77% in adults and peaked twice, first after entering school and then after leaving school. The transmission rate among the preschool children was much lower compared to the results of a rural study in Senegal 1].
TL;DR: It is concluded that Mima mounds are the product of the burrowing of fossorial rodents such as pocket gophers and mole rats, and that these two groups are convergent in morphology, burrowing behavior, and impact on the landscape.
Abstract: The Dalquest-Scheffer Hypothesis that Mima mounds in western North America are the long-term product of burrowing activities of geomyid pocket gophers was tested by examination of areas of similar topography in the highlands of Kenya. Two mound areas, located near Nyahururu at an elevation of about 2,400 m, were studied in detail. The mounds ranged from less than 25 cm to 2 m in height and from a few m to about 20 m in diameter, and were not the remains of large termite nests. Populations of the rhizomyid mole rat, Tachyoryctes splendens, a fossorial rodent similar in morphology and social behavior to geomyid pocket gophers, were associated with these mounds. Mound density and dispersion pattern were similar to North American Mima mounds, and the distribution of fresh soil heaps indicated that the activities of these animals were mound-centered. A shallow laterite hardpan underlay these mound areas, fulfilling another requirement of the Dalquest-Scheffer hypothesis. It is concluded that Mima mounds are the product of the burrowing of fossorial rodents such as pocket gophers and mole rats, and that these two groups are convergent in morphology, burrowing behavior, and impact on the landscape.
TL;DR: One approach is described to define the prevalence and causes of vision loss in Southern Sudan, which is thought to be highly prevalent due to the high prevalence of onchocerciasis and trachoma.
TL;DR: In this paper, the digestibility of treated maize cobs was studied using Romney Marsh wether sheep in a 2 × 3 factorial design, and three chemical treatments were applied to each grinding: distilled water, sodium hydroxide, and Magadi soda.
TL;DR: Present data suggest that body weight, rather than diet, is the more influential factor in reticulo-rumen fermentation rate, and in the molar proportion of fatty acids present.
TL;DR: Immune-precipitation using rabbit anti- Leishmania sera and monoclonal antibodies raised against one of the strains revealed that the 59,000 mol.wt.
TL;DR: Two populations of riverine tiger beetle, one marked and one unmarked, were studied on the banks of the Athi River, Kenya, and behaviour patterns were similar to those observed in North American and European species.
Abstract: Two populations of riverine tiger beetle, one marked and one unmarked, were studied on the banks of the Athi River, Kenya. Behaviour patterns such as hunting, eating, and burrowing, were similar to those observed in North American and European species. High maximum temperatures were avoided either by hunting on wet sand or by digging shallow burrows in wet or damp sand. The temperature range is small at the Athi River compared to a European site which is used for comparison, and thus arrays of thermoregulatory postures are unnecessary. There is some evidence for limited home ranges and for a consistent density at different sites.
RESUME
Le comportement de Lophyridia dongalensis imperatrix: effets des disponibilites en eau sur la strategie de thermoregulation
Deux populations de L. d. imperatrix, l'une marquee, l'autre non, ont ete etudiees sur les rives de la riviere Athi. Des sequences du comportement telles que la chasse, la prise de nourriture et le fouissement etaient semblables a celles observees chez les especes europeennes et nord-americaines.
Les temperatures les plus elevees etaient evitees, soit pendant la chasse en sable humide, soit pendant le fouissage de terriers superficiels dans su sable sec ou humide. La gamme de temperature est faible a Athi par rapport aux sites europeens servant aux comparaisons, et ainsi l'utilisation de postures facilitant la thermoregulation n'est pas necessaire. Il y a quelques preuves d'une limitation des sites utilises et d'une densite en rapport dans differents sites.