A signal-enhanced and sensitive lateral flow aptasensor for the rapid detection of PDGF-BB

Platelet-derived growth factor BB (PDGF-BB) is a potential biomarker of tumor angiogenesis. For the first time, we developed a highly sensitive aptasensor for PDGF-BB with an enhanced test line signal by using two different gold nanoparticles (AuNPs). Herein, we describe a highly sensitive biosensor for PDGF-BB detection that combines biotinylated aptamer on a sample pad and poly thymine-Cy3-AuNP-monoclonal antibody complexes against PDGF-BB immobilized on conjugate pad A. Streptavidin (SA) and rabbit anti-mouse polyclonal antibody were also immobilized in the nitrocellulose membrane at the test and control zones, respectively. When the target PDGF-BB protein was added, it first bound the aptamer, and later the monoclonal antibody to form a biotinylated complex that was captured by SA, resulting in a visual red line on the test zone. In addition, to enhance the sensitivity, another monoclonal antibody against Cy3 was conjugated on AuNP B and immobilized on conjugate pad B to form a AuNPs (A&B)-antibody-(PDGF-BB-Cy3)-aptamer-biotin-SA complex on the test line when a loading buffer was subsequently added. This approach showed a linear response to PDGF-BB from 3 ng mL⁻¹ to 300 ng mL⁻¹ with a limit of detection as low as 1 ng mL⁻¹ obtained in 10 minutes. Our biosensor displayed results through red lines readable by the naked eye. Interestingly, our approach has been successfully applied for real sample verification, proving its applicability for cancer monitoring and diagnosis.

Platelet-derived growth factor BB (PDGF-BB) is a potential biomarker of tumor angiogenesis.     

Selection of potential aptamers for specific growth stage detection of Yersinia enterocolitica

Yersinia enterocolitica remains a threat to public health, and a sensitive detection method is a prerequisite due to its complicated diagnosis associated with slow growth. Recently, aptamer-based detection systems have played a vital role in the development of simple, rapid, sensitive, and specific detection methods. Herein, highly specific ssDNA aptamers were screened against Y. enterocolitica at the different growth stages by whole cell-SELEX. Cells at different growth stages were harvested and incubated with an ssDNA library to get an enriched pool of specific aptamer candidates. After the 10^th round of SELEX, the enriched pool was sequenced and grouped into seven families based on homology and similarity of the secondary structure. Flow cytometry analysis revealed that the aptamers M1, M5, and M7 with K_d values of 37.93 ± 7.88 nM, 74.96 ± 21.34 nM, and 73.02 ± 18.76 nM had the highest affinity and specificity to the target, respectively. The selected aptamers showed binding to the different growth stages of Y. enterocolitica with a significant increase in the gated fluorescence. Our aptamer selection strategy is convenient, and the developed aptamer can be useful for an accurate and reliable detection system.

Yersinia enterocolitica remains a threat to public health, and a sensitive detection method is a prerequisite due to its complicated diagnosis associated with slow growth.     

Bacteriospermia,extended spectrum beta lactamase producing Gram-negative bacteria and other factors associated with male infertility in Mwanza,Tanzania: a need of diagnostic bacteriology for management of male infertility

BackgroundInfections caused by Extended spectrum beta lactamase (ESBL) producing bacterial are global challenge. There is limited information on the magnitude of bacteriospermia, ESBL producing Gram-negative bacteria (GNB) causing bacteriospermia and factors associated with male infertility. This study determined magnitude of bacteriospermia, ESBL-GNB and other factors association with infertility among presumptive infertile men in Mwanza, Tanzania.MethodsA cross-sectional hospital-based study was conducted between May 2017 and July 2018 among 137 presumptive infertile men. Semen specimens were self-collected by masturbation into clean, sterile and none-spermicidal containers and processed following laboratory standard operating procedures (SOPs). Data analysis was done using STATA 13.0.ResultsGram-negative bacteria were predominantly isolated (86.4%), of which 31.6% were ESBL producers. In a total 44 bacteria were isolated from semen culture. The blaCTX-M gene was detected in 75% of phenotypically confirmed ESBL producers. Infertility was independently found to be associated with abnormal spermatozoa morphology (OR (95%CI): 14.48(3.17–66.05)) and abnormal spermatozoa motility (OR (95%CI): 0.05(0.01–0.24)). However, neither bacteriospermia (OR (95%CI): 0.86(0.29–2.59)) nor ESBL bacteriospermia (OR (95%CI): 0.13(0.01–1.22)) was found to be associated with infertility.ConclusionOne third of bacteriospermia is due to ESBL-producers with history of antibiotic use being protective factor for infertility. Abnormal spermatozoa morphology and poor spermatozoa forward motility independently predicted infertility.     

Impact of behaviour change communication interventions on sales of fortified sunflower oil in Tanzania: A spatial–temporal analysis and association study

The Masava project was implemented in Manyara and Shinyanga regions in Tanzania to improve vitamin A intake by making available vitamin A‐fortified sunflower oil with a subsidy through a mobile phone‐based e‐Voucher system. This study was conducted to assess the impact of the behaviour change communication (BCC) campaign of the project on volume of sales of vitamin A‐fortified sunflower oil. The e‐Voucher system provides real‐time data on the number of e‐Vouchers redeemed. The number, type, and locations of BCC events were obtained from the implementation agency. Multivariate linear regression was used to examine the associations between (a) the number and type of BCC events conducted in a ward and the volume of subsequent fortified oil redeemed in the ward and (b) distance of clinic shows, a component of the BCC campaign, from participating retailers and the volume of fortified oil redeemed in the store. After 1 year of the campaign, the volume of fortified oil redeemed monthly increased by more than 5 times in Manyara and by more than three times in Shinyanga. Among the different types of BCC events conducted, only clinic shows and cooking shows were significantly associated with the volume of redemptions (p < .05). Compared with retailers where at least one clinic show was conducted within 0.5 km from its location, the volume of redemptions was significantly lower at retailers where no clinic show conducted within 3.0 km from its location (p < .05). These findings suggest that future health promotion interventions in rural Africa should involve health clinics.     

Investigating Wilms’ Tumours Worldwide: A Report of the OxPLORE Collaboration—A Cross-Sectional Observational Study

Background

Childhood cancer is neglected within global health. Oxford Pediatrics Linking Oncology Research with Electives describes early outcomes following collaboration between low- and high-income paediatric surgery and oncology centres. The aim of this paper is twofold: to describe the development of a medical student-led research collaboration; and to report on the experience of Wilms’ tumour (WT).

Methods

This cross-sectional observational study is reported as per STROBE guidelines. Collaborating centres included three tertiary hospitals in Tanzania, Rwanda and the UK. Data were submitted by medical students following retrospective patient note review of 2 years using a standardised data collection tool. Primary outcome was survival (point of discharge/death).

Results

There were 104 patients with WT reported across all centres over the study period (Tanzania n = 71, Rwanda n = 26, UK n = 7). Survival was higher in the high-income institution [87% in Tanzania, 92% in Rwanda, 100% in the UK (X² 36.19, p < 0.0001)]. Given the short-term follow-up and retrospective study design, this likely underestimates the true discrepancy. Age at presentation was comparable at the two African sites but lower in the UK (one-way ANOVA, F = 0.2997, p = 0.74). Disease was more advanced in Tanzania at presentation (84% stage III–IV cf. 60% and 57% in Rwanda and UK, respectively, X² 7.57, p = 0.02). All patients had pre-operative chemotherapy, and a majority had nephrectomy. Post-operative morbidity was higher in lower resourced settings (X² 33.72, p < 0.0001). Methodology involving medical students and junior doctors proved time- and cost-effective. This collaboration was a valuable learning experience for students about global research networks.

Conclusions

This study demonstrates novel research methodology involving medical students collaborating across the global south and global north. The comparison of outcomes advocates, on an institutional level, for development in access to services and multidisciplinary treatment of WT.