Involvement of N-glycans in binding of Photorhabdus luminescens Tc toxin.

Photorhabdus luminescens Tc toxins are large tripartite ABC-type toxin complexes, composed of TcA, TcB and TcC proteins. Tc toxins are widespread and have shown a tropism for a variety of targets including insect, mammalian and human cells. However, their receptors and the specific mechanisms of uptake into target cells remain unknown. Here, we show that the TcA protein TcdA1 interacts with N-glycans, particularly Lewis X/Y antigens. This is confirmed using N-acetylglucosamine transferase I (Mgat1 gene product)-deficient Chinese hamster ovary (CHO) Lec1 cells, which are highly resistant to intoxication by the Tc toxin complex most likely due to the absence of complex N-glycans. Restoring Mgat1 gene activity, and hence complex N-glycan biosynthesis, recapitulated the sensitivity of these cells to the toxin. Exogenous addition of Lewis X trisaccharide partially inhibits intoxication in wild-type cells. Additionally, sialic acid also largely reduced binding of the Tc toxin. Moreover, proteolytic activation of TcdA1 alters glycan-binding and uptake into target cells. The data suggest that TcdA1-binding is most likely multivalent, and carbohydrates probably work cooperatively to facilitate binding and intoxication.

Comparison of measured and predicted mesiodistal tooth-widths of 13-17 years old Kenyans: a descriptive cross-sectional study to develop a new prediction equation for use in the mixed dentition in a Kenyan population.

BACKGROUND: The Tanaka and Johnson equation is commonly used in mixed dentition analysis. However, the analysis is based on  a Caucasian population making clinical decisions challenging when used in different ethnic groups. This study developed a prediction equation based on a Kenyan population. DESIGN: A descriptive cross-sectional study done in 68 13-17 years old Kenyans of African descent in two boarding secondary schools. Alginate impressions were taken, study models obtained, and mesiodistal tooth-widths measured on upper and lower study models from the first molar to the contralateral first molar. Descriptive statistics, paired t-tests and independent t-tests were conducted and Pearson product-moment correlation coefficients calculated (p < 0.05). RESULTS: The mean age was 13.78 years (SD ± 0.70), females were 59%. The mesiodistal tooth-widths of the permanent canines and premolars were different between males and females (p ˂ 0.1). The Tanaka and Johnston equation significantly under-estimated the mesiodistal tooth-widths of the permanent canines and premolars (p ˂ 0.05). The addition of lower first permanent molars to the permanent lower incisors provided higher correlation coefficients than the Tanaka Johnston equation. CONCLUSIONS: A new equation that includes the permanent lower incisors and first permanent molars as predictor teeth seems to be more suitable for mixed dentition analysis for this Kenyan population. A larger study is needed to validate these findings.

Strengthening community and stakeholder participation in the implementation of integrated vector management for malaria control in western Kenya: a case study.

BACKGROUND: Integrated vector management (IVM) is defined as a rational decision-making process for the optimal use of resources for vector control. The IVM approach is based on the premise that effective control of vectors and the diseases they transmit is not the sole preserve of the health sector. It requires the collaboration and participation of communities and other stakeholders in public and private sectors. Community participation is key to the success of IVM implementation at the local level. CASE DESCRIPTION: The study was conducted in Nyabondo, a rural area of Kenya where malaria is endemic. The objective of the project was to promote adoption and sustainability of IVM and scale up IVM-related activities as well as increase community participation and partnership in malaria control through outreach, capacity-building and collaboration with other stakeholders in the area. Collaboration was pursued through forging partnership with various government departments and ministries, particularly the fisheries department, ministry of education, ministry of health, forestry department and the social services. In total, 33 community-based organizations working within the area were identified and their role documented. Through distribution of information, education and communication (IEC) materials alone, the project was able to reach 10,670 people using various social mobilization methods, such as convening of sensitization meetings-dubbed 'mosquito days'-mainly spearheaded by primary school pupils. A total of 23 local primary schools participated in creating awareness on malaria prevention and control during the project phase. The collaboration with other departments like fisheries led to stocking of more than 20 fishponds with a total of 18,000 fingerlings in the years 2017 and 2018. Fish ponds provided an opportunity for income generation to the community. In partnership with the county government health department, the project was able to re-train 40 CHVs on IVM and malaria case management in the area. Additionally, 40 fish farmers were re-trained on fish farming as part of income generating activity (IGA) while 10 CBOs made up of 509 members received both eucalyptus and Ocimum kilimandscharicum seedlings that were distributed to four CBOs composed of 152 members. Four primary schools made up of 113 health club members also received eucalyptus seedlings as part of IGA in addition to fish farming. In total, around 20,000 eucalyptus seedlings were distributed to the community as part of IGA initiatives. By the end of 2018, the project was able to reach 25,322 people in the community during its two-year advocacy and social mobilization initiatives. CONCLUSION: Through advocacy and social mobilization, the IVM strategy improved inter-sectoral collaboration, enhanced capacity building and community participation. However, more IVM related activities are needed to effectively mobilize available resources and increase community participation in malaria control.

Long lasting insecticidal mosquito nets (LLINs) ownership, use and coverage following mass distribution campaign in Lake Victoria basin, Western Kenya.

BACKGROUND: Long-lasting insecticidal nets (LLINs) are the most widely used malaria prevention and control intervention in Africa. However, their effectiveness may vary depending on their local geographic coverage, ownership and use at household level. This study aimed at assessing LLINs ownership and use following mass distribution campaign in western Kenya. METHODS: A cross-sectional study was conducted in November 2017. A total of 160 households were randomly selected from 16 villages. Structured questionnaires were used to collect data on households' knowledge on malaria, LLINs ownership, utilization and their perceived benefits. Data was analyzed using IBM Statistical Package for Social Sciences (SPSS) version 21 for windows. Variables were presented as proportions and associations between variables tested using Pearson's chi-square test. RESULTS: Malaria was reported to be the most frequently occurring disease (87.5%) in the area. Children under 5 years of age were reported to be at higher risks of malaria infection (28.6%). Around 31% of the respondents reported to have at least one member of the household sick with malaria a week before the interview. Commonly cited signs and symptoms of malaria were; fever (24.1%), headache (17.7%), vomiting (14.5%) feeling cold (12.6%) and loss of appetite (10%). There were 382 reported LLINs among 753 occupants in the 160 households surveyed. The average LLIN ownership was 2.4 nets per household and 1.97 persons per LLIN. Among the surveyed households, 96.9% owned at least one LLIN and 64.1% owned at least one LLIN for every two people. Among those who owned LLINs, 98.1% reported using them the previous night. Ownership per household ranged from 0 to 6 with a mean of 2.39. More than three quarter of the nets were acquired through free mass distribution campaigns and 80% were acquired less than 6 months prior to the survey. CONCLUSION: Despite high net coverage and use, a number of households experienced malaria episodes in the study area. There is need to investigate the likelihood of outdoor malaria transmission and assess the physical integrity of the existing LLINs and their insecticidal effectiveness in protecting household members against malaria.

Photorhabdus luminescens Tc toxin is inhibited by the protease inhibitor MG132 and activated by protease cleavage resulting in increased binding to target cells.

Photorhabdus luminescens Tc toxins consist of the cell-binding component TcA, the linker component TcB, and the enzyme component TcC. TccC3, a specific isoform of TcC, ADP-ribosylates actin and causes redistribution of the actin cytoskeleton. TccC5, another isoform of TcC, ADP-ribosylates and activates Rho proteins. Here, we report that the proteasome inhibitor MG132 blocks the intoxication of cells by Tc toxin. The inhibitory effect of MG132 was not observed, when the ADP-ribosyltransferase domain of the TcC component was introduced into target cells by protective antigen, which is the binding and delivery component of anthrax toxin. Additionally, MG132 affected neither pore formation by TcA in artificial membranes nor binding of the toxin to cells. Furthermore, the in vitro ADP-ribosylation of actin by the enzyme domain of TccC3 was not affected by MG132. Similar to MG132, several calpain inhibitors blocked the action of the Tc toxin. Proteolytic cleavage of the binding component TcA induced by P. luminescens protease PrtA1 or by collagenase largely increased the toxicity of the Tc toxin. MG132 exhibited no inhibitory effect on the cleaved TcA component. Moreover, binding of TcA to target cells was largely increased after cleavage. The data indicate that Tc toxin is activated by proteolytic processing of the TcA component, resulting in increased receptor binding. Toxin processing is probably inhibited by MG132.

Evaluating effectiveness of screening house eaves as a potential intervention for reducing indoor vector densities and malaria prevalence in Nyabondo, western Kenya.

BACKGROUND: Mosquito-proofing of houses using wire mesh screens is gaining greater recognition as a practical intervention for reducing exposure to malaria transmitting mosquitoes. Screening potentially protects all persons sleeping inside the house against transmission of mosquito-borne diseases indoors. The study assessed the effectiveness of house eaves screening in reducing indoor vector densities and malaria prevalence in Nyabondo, western Kenya. METHODS: 160 houses were selected for the study, with half of them randomly chosen for eaves screening with fibre-glass coated wire mesh (experimental group) and the other half left without screening (control group). Randomization was carried out by use of computer-generated list in permuted blocks of ten houses and 16 village blocks, with half of them allocated treatment in a ratio of 1:1. Cross-sectional baseline entomological and parasitological data were collected before eave screening. After baseline data collection, series of sampling of indoor adult mosquitoes were conducted once a month in each village using CDC light traps. Three cross-sectional malaria parasitological surveys were conducted at three month intervals after installation of the screens. The primary outcome measures were indoor Anopheles mosquito density and malaria parasite prevalence. RESULTS: A total of 15,286 mosquitoes were collected over the two year period using CDC light traps in 160 houses distributed over 16 study villages (mean mosquitoes = 4.35, SD = 11.48). Of all mosquitoes collected, 2,872 (18.8%) were anophelines (2,869 Anopheles gambiae sensu lato, 1 Anopheles funestus and 2 other Anopheles spp). Overall, among An. gambiae collected, 92.6% were non-blood fed, 3.57% were blood fed and the remaining 0.47% were composed of gravid and half gravid females. More indoor adult mosquitoes were collected in the control than experimental arms of the study. Results from cross-sectional parasitological surveys showed that screened houses recorded relatively low malaria parasite prevalence rates compared to the control houses. Overall, malaria prevalence was 5.6% (95% CI: 4.2-7.5) n = 1,918, with baseline prevalence rate of 6.1% (95% CI: 3.9-9.4), n = 481 and 3rd follow-up survey prevalence of 3.6% (95% CI: 2.0-6.8) n = 494. At all the three parasitological follow-up survey points, house screening significantly reduced the malaria prevalence by 100% (p < 0.001), 63.6% (p = 0.026), and 100% (p < 0.001) in the 1st, 2nd and 3rd follow-up surveys respectively. CONCLUSIONS: The study demonstrated that house eave screening has potential to reduce indoor vector densities and malaria prevalence in high transmission areas.

Evaluating the impact of larviciding with Bti and community education and mobilization as supplementary integrated vector management interventions for malaria control in Kenya and Ethiopia.

BACKGROUND: Malaria prevention in Africa is mainly through the use of long-lasting insecticide treated nets (LLINs). The objective of the study was to assess the effect of supplementing LLINs with either larviciding with Bacillus thuringiensis israelensis (Bti) or community education and mobilization (CEM), or with both interventions in the context of integrated vector management (IVM). METHODS: The study involved a factorial, cluster-randomized, controlled trial conducted in Malindi and Nyabondo sites in Kenya and Tolay site in Ethiopia, to assess the impact of the following four intervention options on mosquitoes and malaria prevalence: LLINs only (arm 1); LLINs and Bti (arm 2); LLINs and CEM (arm 3); and, LLINs combined with Bti and CEM (arm 4). Between January 2013 and December 2015, CDC light traps were used to sample adult mosquitoes during the second, third and fourth quarter of each year in 10 houses in each of 16 villages at each of the three study sites. Larvae were sampled once a fortnight from potential mosquito-breeding habitats using standard plastic dippers. Cross-sectional malaria parasite prevalence surveys were conducted involving a total of 11,846 primary school children during the 3-year period, including 4800 children in Tolay, 3000 in Malindi and 4046 in Nyabondo study sites. RESULTS: Baseline relative indoor anopheline density was 0.11, 0.05 and 0.02 mosquitoes per house per night in Malindi, Tolay and Nyabondo sites, respectively. Nyabondo had the highest recorded overall average malaria prevalence among school children at 32.4%, followed by Malindi with 5.7% and Tolay 1.7%. There was no significant reduction in adult anopheline density at each of the three sites, which could be attributed to adding of the supplementary interventions to the usage of LLINs. Malaria prevalence was significantly reduced by 50% in Tolay when using LLINs coupled with application of Bti, community education and mobilization. The two other sites did not reveal significant reduction of prevalence as a result of combining LLINs with any of the other supplementary interventions. CONCLUSION: Combining LLINs with larviciding with Bti and CEM further reduced malaria infection in a low prevalence setting in Ethiopia, but not at sites with relatively higher prevalence in Kenya. More research is necessary at the selected sites in Kenya to periodically determine the suite of vector control interventions and broader disease management strategies, which when integrated would further reduce adult anopheline populations and malaria prevalence beyond what is achieved with LLINs.

Community knowledge and perceptions on malaria prevention and house screening in Nyabondo, Western Kenya.

BACKGROUND: Screening of houses to prevent mosquito entry is increasingly being recommended as an effective and practical method against malaria transmission through reduced human-mosquito contact. The objective of the study was to assess community knowledge and perceptions on malaria prevention and house screening in a malaria endemic area of Western Kenya. METHODS: A cross-sectional household survey was conducted in 2017 in Nyabondo area of western Kenya. A total of 80 households were randomly selected to participate in the study within 16 villages. Structured questionnaires, focus group discussions and key informant interviews were used to collect data. RESULTS: A total of 80 respondents participated in the survey and more than half (53.8%) reported to have attained primary education. About 91% of the respondents had previously seen or heard malaria messages and this was associated with the respondents level of education (χ2 = 10.163; df 4; P = 0.038, 95% CI). However, other variables like gender, marital status, religion and occupation were not significantly associated with knowledge in malaria. Insecticide treated mosquito nets was by far the most reported known (97.4%) and applied (97.6%) personal protective while only 15.6% respondents were aware of house screening. The major reason given for screening doors, windows and eaves was to prevent entry of mosquito and other insects (> 85%). Lack of awareness was the major reason given for not screening houses. Grey colour was the most preferred choice for screen material (48%), and the main reason given was that grey matched the colour of the walls (21%) and did not 'gather' dust quickly. CONCLUSION: House screening was not a common intervention for self-protection against malaria vectors in the study area. There is need to advocate and promote house screening to increase community knowledge on this as an additional integrated vector management strategy for malaria control.

Reconstruction of persistent oronasal communication using an anteriorly based tongue flap following failed cleft palate repair-Report of two cases.

The tongue flap is a suitable alternative to local mucoperiosteal flaps in closure of wide, persistent oronasal communications, surrounded by scarred and fibrotic tissue as a result of previously attempted palatoplasty. Herein, we report two cases with large recurrent oronasal communication closed using the anteriorly based dorsal tongue flap.

An innovative approach in the management of alveolar clefts with bone graft harvest from maxillary tuberosity and mandibular wisdom molar odontectomy sites: A case report.

Alveolar bone grafting is a complex procedure utilized in alveolar cleft repair; however, the ideal site of bone graft material remains highly debated. In this study, we describe the management of a 14-year-old girl with bilateral alveolar clefts using alternative intraoral donor sites for bone graft harvest.

Bed net use and associated factors in a rice farming community in Central Kenya.

BACKGROUND: Use of insecticide-treated nets (ITNs) continues to offer potential strategy for malaria prevention in endemic areas. However their effectiveness, sustainability and massive scale up remain a factor of socio-economic and cultural variables of the local community which are indispensable during design and implementation stages. METHODS: An ethnographic household survey was conducted in four study villages which were purposefully selected to represent socio-economic and geographical diversity. In total, 400 households were randomly selected from the four study villages. Quantitative and qualitative information of the respondents were collected by use of semi-structured questionnaires and focus group discussions. RESULTS: Malaria was reported the most frequently occurring disease in the area (93%) and its aetiology was attributed to other non-biomedical causes like stagnant water (16%), and long rains (13%). Factors which significantly caused variation in bed net use were occupant relationship to household head (chi2 = 105.705; df 14; P = 0.000), Age (chi2 = 74.483; df 14; P = 0.000), village (chi2 = 150.325; df 6; P = 0.000), occupation (chi2 = 7.955; df 3; P = 0.047), gender (chi2 = 4.254; df 1; P = 0.039) and education levels of the household head or spouse (chi2 = 33.622; df 6; P = 0.000). The same variables determined access and conditions of bed nets at household level. Protection against mosquito bite (95%) was the main reason cited for using bed nets in most households while protection against malaria came second (54%). Colour, shape and affordability were some of the key potential factors which determined choice, use and acceptance of bed nets in the study area. CONCLUSION: The study highlights potential social and economic variables important for effective and sustainable implementation of bed nets-related programmes in Sub-Saharan Africa.

Esthetic preferences of European American, Hispanic American, Japanese, and African judges for soft-tissue profiles.

INTRODUCTION: Our objectives were to determine whether observer and patient sex and race or ethnicity determine esthetic preferences for lip positions. METHODS: Four independent panels each consisting of 30 lay judges viewed pretreatment silhouette profiles of 10 European American, 10 Japanese, and 10 African American Angle Class I and Class II orthodontic patients. The panels included European Americans, Hispanic Americans, Japanese, and Africans. Profiles were traced from lateral cephalograms and manipulated so that the lip profile lay on the Ricketts' E-line or at various distances from the E-line from -8 to +4 mm in 2-mm increments. The judges selected the profile that they considered the most attractive and then classified the remaining 6 profiles as either acceptable or unacceptable. RESULTS: The mean preferred lip positions (mean +/- SD) were -2.58 +/- 1.92 mm for European American, -3.28 +/- 2.26 mm for Hispanic American, -3.45 +/- 1.92 mm for Japanese, and -2.13 +/- 1.95 mm for African judges. The African judges preferred more protrusive profiles compared with the Hispanic American (P <0.01) and Japanese (P <0.001) judges. Patient race or ethnicity and sex also contributed significantly to the judgments of profile esthetics (P <0.001). CONCLUSIONS: Judge race or ethnicity and patient race or ethnicity and sex significantly influence laypersons' standards for lip profile esthetics.

Engineering Photorhabdus luminescens toxin complex (PTC) into a recombinant injection nanomachine.

Engineering delivery systems for proteins and peptides into mammalian cells is an ongoing challenge for cell biological studies as well as for therapeutic approaches. Photorhabdus luminescens toxin complex (PTC) is a heterotrimeric protein complex able to deliver diverse protein toxins into mammalian cells. We engineered the syringe-like nanomachine for delivery of protein toxins from different species. In addition, we loaded the highly active copepod luciferase Metridia longa M-Luc7 for accurate quantification of injected molecules. We suggest that besides the probable size limitation, the charge of the cargo also influences the efficiency of packing and transport into mammalian cells. Our data show that the PTC constitutes a powerful system to inject recombinant proteins, peptides, and potentially, other molecules into mammalian cells. In addition, in contrast to other protein transporters based on pore formation, the closed, compact structure of the PTC may protect cargo from degradation.

Malaria vector control practices in an irrigated rice agro-ecosystem in central Kenya and implications for malaria control.

BACKGROUND: Malaria transmission in most agricultural ecosystems is complex and hence the need for developing a holistic malaria control strategy with adequate consideration of socio-economic factors driving transmission at community level. A cross-sectional household survey was conducted in an irrigated ecosystem with the aim of investigating vector control practices applied and factors affecting their application both at household and community level. METHODS: Four villages representing the socio-economic, demographic and geographical diversity within the study area were purposefully selected. A total of 400 households were randomly sampled from the four study villages. Both semi-structured questionnaires and focus group discussions were used to gather both qualitative and quantitative data. RESULTS: The results showed that malaria was perceived to be a major public health problem in the area and the role of the vector Anopheles mosquitoes in malaria transmission was generally recognized. More than 80% of respondents were aware of the major breeding sites of the vector. Reported personal protection methods applied to prevent mosquito bites included; use of treated bed nets (57%), untreated bed nets (35%), insecticide coils (21%), traditional methods such as burning of cow dung (8%), insecticide sprays (6%), and use of skin repellents (2%). However, 39% of respondents could not apply some of the known vector control methods due to unaffordability (50.5%), side effects (19.9%), perceived lack of effectiveness (16%), and lack of time to apply (2.6%). Lack of time was the main reason (56.3%) reported for non-application of environmental management practices, such as draining of stagnant water (77%) and clearing of vegetations along water canals (67%). CONCLUSION: The study provides relevant information necessary for the management, prevention and control of malaria in irrigated agro-ecosystems, where vectors of malaria are abundant and disease transmission is stable.

Effect of health education on oral hygiene and gingival status of persons living with HIV attending comprehensive care centres in Nairobi, Kenya.

The study aimed to describe the effect of an oral health education intervention on oral hygiene status and gingival inflammation among persons with HIV attending two comprehensive healthcare centres in Nairobi, Kenya. This was a quasi-experimental study of 195 participants (with 102 in the intervention group, and 93 serving as the control group) who were selected using stratified random sampling. The data were collected at baseline, at three months (review 1), and at six months (review 2) using an interviewer-administered World Health Organization clinical examination form. The prevalence of plaque among the participants in the intervention decreased from 70.6% to 18.6%, with a significant decrease in their mean plaque score, from 0.89 to 0.15. The prevalence of gingival inflammation in the intervention group decreased from 58.2% to 12.7%, with a significant decrease in the mean gingival score, from 0.66 to 0.11. No significant change in degree of oral hygiene and gingival inflammation was observed among the non-intervention group. There was a strong association between the change in the mean gingival score and the change in the mean plaque score between baseline and at six months for the intervention group. The regression analysis yielded a coefficient of determination (r2) of 0.76; therefore, 76% of the variation in change in gingival score was explained by the variables in the equation. Only the change in mean plaque score was a significant predictor of the change in gingival score.