Showing papers by "University of Nairobi published in 1996"

A human MSX1 homeodomain missense mutation causes selective tooth agenesis

Abstract: We demonstrate that a mutation in the homeobox gene, MSX1, causes a common developmental anomaly, familial tooth agenesis. Genetic linkage analyses in a family with autosomal dominant agenesis of second premolars and third molars identified a locus on chromosome 4p, where the MSX1 gene resides. Sequence analyses demonstrated an Arg31Pro missense mutation in the homeodomain of MSX1 in all affected family members. Arg 31 is a highly conserved homeodomain residue that interacts with the ribose phosphate backbone of target DNA. We propose that the Arg31 Pro mutatrion comprises MSX1 interactions, and suggest that MSX1 functions are critical for normal development of specific human teeth.

Focused Peer-Mediated Educational Programs Among Female Sex Workers To Reduce Sexually Transmitted Disease And Human Immunodeficiency Virus Transmission In Kenya And Zimbabwe

Abstract: Peer-mediated education programs in Kenya and Zimbabwe focusing on female sex workers for the control of human immunodeficiency virus (HIV) infection and other sexually transmitted diseases (STDs) have led to increased condom use and increased adoption of other safer sex practices, as well as declines in STD and HIV incidence among female sex workers. It is likely that similar declines have occurred among their clients and possibly in the general community, although supporting data are limited. These results are encouraging. However, progress in increasing the scale and coverage of intervention programs among female sex workers has been slow. Constraints to expanding program coverage include inadequate political commitment; deficiencies in program planning, management, and human resources; and insufficient funding. The challenges currently are to show that behavioral change can be sustained and to scale up activities from small demonstration projects to district, provincial, and national levels.

Investigating The Influence Of Synoptic-scale Monsoonal Winds And Mesoscale Circulations On Diurnal Weather Patterns Over Kenya Using A Mesoscale Numerical Model

Abstract: The Regional Atmospheric Modeling System (RAMS) developed at Colorado State University (CSU) was used to investigate the influence of the large-scale monsoonal winds and the mesoscale local circulations on the diurnal precipitation pattern over Kenya. Three basic experiments were performed. In the first control experiment (CONTROL), RAMS was initialized using observational data (“variable initialization”) from the global analyzed ECMWF 2.5° × 2.5° data of 0000 UTC 14 April 1985. The model was integrated forward in time for 24 h to simulate the large-scale flow fields over Kenya. Full physics including moist convection were implemented in the model. The model outputs were validated against available observations in order to determine the ability of the model in replicating the synoptic climatology prevailing over the study domain. In the. second experiment (MESO), the model simulation was started from an atmosphere at rest in order to exclude the large-scale flow from the model runs. This experime...

Genital ulcer disease among STD clinic attenders in Nairobi: association with HIV-1 and circumcision status

Abstract: In previous studies, genital ulcers in men have been found to be associated with increased risk of HIV-1 seroconversion. To further explore this association male patients attending a sexually transmitted disease (STD) clinic in Nairobi for either urethritis (controls, n = 276) or a genital ulcer (cases, n = 607) were compared with respect to sexual behaviour, presence of HIV-1 antibody and circumcision status. Patients were followed to study risk factors for incident genital ulcers and HIV-1 seroconversion. At entry, being married was associated with higher prevalence of HIV-1 (OR = 1.76) and genital ulcers (OR = 1.42). Lack of circumcision was associated with both HIV-1 infection (OR = 4.67) and the presence of a genital ulcer (OR = 2.23). Genital ulcers were also associated with HIV-1 infection (OR = 1.87) independent of circumcision status. On follow-up, HIV-1 seropositivity was associated with incident genital ulcers. It is argued that the association between genital ulcers and HIV-1 infection may be more complex than ulcers simply being a risk factor for HIV-1 infection, and that HIV-1 infection may either increase the risk of acquiring a genital ulcer, or HIV-1 infection and genital ulcers may have some unknown risk factor in common.

Neoplastic cells of hodgkin's disease show differences in ebv expression between kenya and italy

Abstract: The Epstein-Barr Virus (EBV) has been implicated in the pathogenesis of Hodgkin's disease (HD). However, the association of EBV with this disease varies greatly from series to series and from country to country. Epidemiological studies have shown differences in HD occurring in different parts of the world. In particular, it has been reported that HD in developing countries differs from HD in Western countries in terms of epidemiological, pathological and clinical characteristics. These discrepancies among populations suggest an interaction with environmental factors and a direct role of different etiological agents. At present, there are no data on the frequency of association of EBV with HD in equatorial Africa. In this study, a large series of HD cases have been collected at the University of Nairobi, Kenya, and at the Universities of Bologna and Siena, Italy. The cases have been reviewed and classified according to the REAL Classification and the presence of EBV has been assessed by in situ hybridization (ISH). A statistical difference in EBV expression was found between HD from Kenya and HD from Italy. EBV-positive neoplastic cells were detected in 92% of Kenyan cases, whereas only 48% of Italian cases showed EBER1/2 positivity in the neoplastic cells. Our results suggest that, in Kenya, EBV plays a more direct role in the pathogenesis of HD, as it does for endemic Burkitt lymphoma.

The prevalence of malocclusion in 13- to 15-year-old children in Nairobi, Kenya.

Abstract: Data on occlusal features and the need for orthodontic treatment in Kenya is scanty. This study was carried out to determine the prevalence of malocclusion in children in Nairobi, Kenya. Nine hundred and nineteen children aged 13–15 years (468 male, 451 female) were examined. The registration method used was that described by Bjork et al. The prevalence of malocclusion was 72%. The predominant anteroposterior relationship of die dental arches was neutral occlusion (93%). Specific malocclusion traits were highest for crowding (19%), rotations (19%), posterior crossbite (10%), maxillary overjet (10%), and frontal open bite (8%). There was no statistically significant difference in die overall prevalence of malocclusion between males and females, but some occlusal traits were significandy higher in males. Although the findings indicate that the present population is not characterized by a substantial difference in the overall prevalence of malocclusion compared with other communities, some traits differed in...

Lay perceptions of risk of HIV infection and the social construction of safer sex: Some experiences from Kenya

Abstract: Safer sex in the context of HIV/AIDS control in Kenya has mainly been promoted through the encouragement of condom use. In this strategy, safer sex is treated as though it is synonymous with condom use. This paper, which is based on ethnographic data drawn from a sample of 29 heterosexual HIV-positive patients presenting in four specialized treatment clinics in Nairobi, questions this assumption by examining some particular ways in which risks of HIV/AIDS are socially constructed, and how these perceptions have informed lay experiences of safer sex in Nairobi. The paper further examines the juxtaposition of common-sense and biomedical knowledge in producing socially meaningful experiences of safer sex. The implications of these lay safer sex constructions and experiences for government-sponsored HIV/AIDS control programmes and policies are discussed.

Contraceptive use and HIV infection in Kenyan family planning clinic attenders.

Abstract: This pilot study aimed to determine the feasibility of a larger study of contraception and risk of HIV infection in women. We also measured risk factors for and occurrence of HIV infection in the participants. A cohort of 1537 seronegative women attending a family planning clinic in Nairobi, Kenya was enrolled and followed for up to 12 months per woman. HIV testing was done quarterly. A nested case-control analysis was done with seroconverting women (cases) and 3 matched controls per case, who had detailed interviews and received physical examinations and STD tests. The prevalence of HIV at enrollment was 6.1%; seropositive women were excluded from further analysis. The 12-month life-table cumulative incidence of HIV was 2.1 per 100 women (95% confidence interval [CI] 1.1-3.2). In the nested case-control analysis (17 cases and 51 controls), the crude odds ratio of HIV infection comparing oral contraceptive (OC) users with other women was 3.5 (95%) CI 0.8-21.5), which persisted after control for single confounders at a time. The putative association between OC use sand HIV infection is critical to public health policy, yet no study has been conducted specifically to measure it, yielding weak and conflicting evidence. We intend to conduct a larger study with a similar design as the current pilot study, which confirmed the feasibility of a more definitive project.

Long-term use of permethrin-impregnated nets does not increase Anopheles gambiae permethrin tolerance.

Abstract: . Previous use of permethrin-impregnated bednets (mosquito nets) and curtains in four Kenyan villages for one year, 1990-91, raised the permethrin LT50 of Anopheles gambiae to 2.4-fold above its baseline value, designated permethrin tolerance (PT), as measured by exposure to 0.25% permethrin-impregnated papers in W.H.O. test-kits. During 1992-93, with ongoing use of permethrin-impregnated nets and curtains, PT regressed slightly compared with the contemporary susceptibility level of An. gambiae from non-intervention villages, to 1.8-fold in 1992 and only 1.6-fold in 1993. Thus the selection pressure of impregnated nets for PT in Angambiae appears to be minimal in our study villages, although the impact of permethrin was demonstrated by a significantly lower parous-rate of Angambiae females in the intervention (63–66%) than in non-intervention (79%) villages, and by reduced malaria transmission (reported elsewhere). In a selected stock of An. gambiae from the study area, PT did not affect the susceptibility to deltamethrin, fenitrothion, propoxur or DDT. Bioassays described herein provide easy procedures for field-monitoring of mosquito susceptibility/tolerance/resistance to insecticides used for net impregnation in operational programmes.

Increased Risk of Infection with Human Immunodeficiency Virus Type 1 Among Uncircumcised Men Presenting with Genital Ulcer Disease in Kenya

Abstract: The factors responsible for the explosive spread of human immunodeficiency virus type 1 (HIV-1) in sub-Saharan Africa continue to be identified and debated. One of the most controversial factors has been male circumcision. This cross-sectional study was conducted to measure the association between circumcision status and infection with HIV-1 among men with genital ulcer disease. Eight hundred and ten men participated in the study, of whom 190 (23%) were HIV-1-positive. A logistic regression model adjusted for behavioral and historical showed that HIV-1 positivity was independently associated with being uncircumcised (adjusted odds ratio [OR], 4.8; 95% confidence interval [CI], 3.3-7.2) and with a history of urethral discharge (adjusted OR, 2.0; 95% CI, 1.4-2.8). This association could not be explained by measures of sexual exposure to HIV-1 among this population. Male circumcision should be considered as an intervention strategy for AIDS control.

Isolation of alkaloidal constituents of Zanthoxylum usambarense and Zanthoxylum chalybeum using ion-pair HPLC

Abstract: Quaternary alkaloids of two Kenyan medicinal plants belonging to the genus Zanthoxylum, Z. usambarense and Z. chalybeum, were examined using ion-pair HPLC. Both plants contained similar alkaloids, but colored protoberberines were found only in Z. chalybeum. From the stems of Z. usambarense a new alkaloid named usambanoline (1) was isolated and characterized.

Respiratory Physiology of the Lake Magadi Tilapia (Oreochromis alcalicus grahami), a Fish Adapted to a Hot, Alkaline, and Frequently Hypoxic Environment

Abstract: The tilapia Oreochromis alcalicus grahami is a unique ureotelic teleost, the only fish that lives in the alkaline hotsprings of Lake Magadi, Kenya. Physical conditions and fish behavior were monitored in the Fish Springs Lagoon area, a site where the tilapia were particularly abundant. Water Po₂ and temperature fluctuated more or less in parallel in a diurnal cycle from less than 20 Torr and less than 25° C at night to greater than 40° Torr and 38° C during the day, whereas pH remained constant at approximately 9.8. Field laboratory tests demonstrated that routine $\dot{M}o_{}$ (under normoxia) increased greatly from 27° C to 36° C ($Q_{10}$ = 62) but then stabilized at a very high level (~34.5 μmol $g^{-1}$ $h^{-1}$) up to the lethal temperature (~ 42.5° C), a pattern that was adaptive to the natural diurnal regime. The Po₂ threshold for survival during acute exposure (≤ 1 h) was approximately 16 Torr. $\dot{M}o_{2}$ from water was well maintained down to a Po₂ of 60 Torr, below which it declined. Under ...

Analysis of trophic relationships in two shallow equatorial lakes Lake Naivasha (Kenya) and Lake Ihema (Rwanda) using a multispecifies trophic model

Abstract: A multispecifies trophic model called ECOPATH II, which can be used to describe the trophic relationships in aquatic ecosystems on a quantitative basis, is briefly presented. When properly used, it can help to explain the trophic relationships in ecosystems and possible evolution of fishstocks after modifications of the environment (e.g. eutrophication, introduction of a new population and/or a significant increase of the fishing effort), and to compare the trophic structure of several ecosystems. Examples are provided on two shallow lakes: Lake Ihema and Lake Naivasha. They are compared with Lake George which was previously documented.

Acceptability and discontinuation of Depo-Provera, IUCD and combined pill in Kenya.

Abstract: This paper reports on a prospective study conducted between June 1990 and June 1992 to determine method acceptability user satisfaction and continuation rates for three highly effective and reversible contraceptive methods currently available in Kenya: the CuT 380A IUD; the injectable Depo-Provera; and the low-dose oral contraceptive Microgynon. A nonrandomized sample of volunteer participants was used. 1076 users were followed up for a period of 1 year or up to the time of discontinuation of the method whichever came earlier. Analysis revealed method-specific differences in users characteristics. The OC users were younger and had fewer children than the IUD or Depo-Provera users. The Depo-Provera users were older and had the largest family sizes. Many OC users (almost 40%) were single while almost three-quarters of the IUD and Depo-Provera users were married. IUD users were also more educated compared to OC and Depo-Provera users. Survival analysis was used to calculate cumulative life table discontinuation rates by method for the 12-month period. Discontinuation rates were highest for OC users (80%) lowest for IUD users (20%) and intermediate for Depo-Provera users (39%). 90% of OC and Depo-Provera users and 86% of IUD users said they were satisfied with their respective methods. While OCs are among the most popular family planning methods in Kenya they are also one of the most problematic while IUDs have shown the fewest compliance problems. Service providers need to address the issue of high discontinuation rates among young OC users. (authors modified)

Presumptive specific clinical diagnosis of genital ulcer disease (GUD) in a primary health care setting in Nairobi.

Abstract: During a 12-month period in 1990-1991 in Kenya 1076 of 22274 patients (4.8% of all patients over 12 years of age) presented at the Langata Health Center in Nairobi with symptoms of a sexually transmitted disease (STD). Researchers analyzed data on 980 of these patients whose records had complete data to assess the use of presumptive specific clinical diagnosis in the management of STDs in a primary health clinic. 17.1% (168) had genital ulcer disease (GUD). Men were more likely to have a GUD than women (24.7% vs. 10.4%). Haemophilus ducreyi the etiologic agent of chancroid was isolated in the cultures of 40% of the patients with a presumptive specific clinical diagnosis of chancroid compared with 17% of those with a presumptive specific clinical diagnosis of syphilis herpes or lymphogranuloma venereum (LGV) (p = 0.02). The clinical diagnoses of these two GUDs had only a weak correlation with microbiological and serological diagnoses (p = 0.13). 24% of patients with a presumptive specific clinical diagnosis of syphilis 31% of those with a presumptive specific clinical diagnosis of chancroid 6% of those with a specific clinical diagnosis of genital herpes or LGV and 4.7% of those who had no GUD disease tested positive for syphilis (p < 0.001 GUD vs. no GUD). Among patients with syndromic diagnosis of GUD the presumptive specific clinical diagnosis of chancroid had a high sensitivity (91%) low specificity (24%) and low positive predictive value (40%). Among patients with syndromic diagnosis of syphilis the presumptive specific clinical diagnosis of syphilis had a low sensitivity (25%) higher specificity (87%) and low positive predictive value (24%). 13% of patients with positive cultures for H. ducreyi did not receive a recommended or effective drug for chancroid. 82% of patients who tested positive for syphilis did not receive a recommended drug for syphilis. Based on these findings the researchers conclude that syndromic treatment of GUD with use of antimicrobial combinations active against both chancroid and syphilis is a better course of treatment than use of single drugs based on presumptive specific clinical diagnoses for this population.

Zona pellucida antigens: targets for contraceptive vaccines.

Abstract: The mammalian ovary is unique among secretory organs in its ability both to produce the female gamete and to provide the necessary endocrine support for its orderly development. This set of functions utilizes complex feedback mechanisms involving the hypothalamus and the anterior pituitary over the reproductive life of the individual. The late stages of follicular development just prior to ovulation have been the focus of most ovarian studies. However, it is necessary to investigate the earliest stages of follicular development in order to begin to understand the foundations of immunologically based interference with ovarian function.

Role of shops and shopkeepers in malaria control.

Abstract: A study was carried out to determine the range of antimalarial drugs stocked and also to determine the knowledge and practice patterns of shopkeepers and their customers on antimalarial products stocked and bought. It was hoped that the information thus obtained could be used to improve the selling and buying practices and hence contribute positively to malaria control. Up to seventeen different brands of antimalarial drugs including thirteen different brands of chloroquine and four different second line drugs were stocked by shopkeepers. A multiplicity of drugs, dosages and combinations were used for treating malaria. Only 38% of the shopkeepers felt they knew enough on the use of the drugs used in the treatment of malaria while 23% of the customers felt they knew enough on the use of the drugs. Most of the respondents wanted to know more on the use of the drugs. Knowledge desired by the shopkeepers included the correct dosage, combination with other drugs and side effects while information needed by the customers was on correct dosage, combination with other drugs as well as adverse effects. The person mentioned by the shopkeepers and the consumers to be in the best position to give the information was the doctor. The dissemination method preferred by the shopkeepers as well as the consumers was the radio.

Effective thermal conductivity of loose particulate systems

Abstract: The effective thermal conductivity for several loose particulate insulation systems has been measured in the temperature range from 273 K–900 K and the results compared to those predicted from three different models. The measured thermal conductivities increase with temperature. This is accounted for in terms of increased conduction by the fluid (air) and the radiative heat transfer through the media although the latter mode of heat transfer is relatively suppressed in materials containing finer particles. The model due to Zumbrunnen et al. [1] was found to predict values that closely agreed with the experimental values.