Clarence S. Yah

Challenges facing sterilization and depyrogenation of nanoparticles: Effects on structural stability and biomedical applications

This review outlines and compares techniques that are currently available for the sterilization of nanoparticles and addresses the topic of endotoxin contamination. Several techniques are available for the removal of microbial contamination from nanoparticles developed for use in nanomedicine applications. These techniques include filtration, autoclaving and irradiation, as well as formaldehyde, ethylene oxide and gas plasma treatments. Of these sterilization methodologies, filtration may potentially remove microbial contamination without altering the physicochemical properties of the carrier nanoparticles, nor affecting their toxicity and functionality. However, no single process may be applied to all nanoparticle preparations and, therefore, it is recommended that each nanoparticle-drug system be validated on a case-by-case basis. From the clinical editor: This comprehensive review covers the currently available methods for removal of microbial contaminations from nanoparticles for nanomedicine applications. The review highlights the pros and cons of each available method. Authors conclude that there is no single best method and recommend a customized approach for each nanoparticle system.

The production of carbon nanotubes from carbon dioxide: challenges and opportunities

Abstract Recent advances in the production of carbon nanotubes (CNTs) are reviewed with an emphasis on the use of carbon dioxide (CO2) as a sole source of carbon. Compared to the most widely used carbon precursors such as graphite, methane, acetylene, ethanol, ethylene, and coal-derived hydrocarbons, CO2 is competitively cheaper with relatively high carbon yield content. However, CNT synthesis from CO2 is a newly emerging technology, and hence it needs to be explored further. A theoretical and analytical comparison of the currently existing CNT-CO2 synthesis techniques is given including a review of some of the process parameters (i.e., temperature, pressure, catalyst, etc.) that affect the CO2 reduction rate. Such analysis indicates that there is still a fundamental need to further explore the following aspects so as to realize the full potential of CO2 based CNT technology: (1) the CNT-CO2 synthesis and formation mechanism, (2) catalytic effects of transitional metals and mechanisms, (3) utilization of metallocenes in the CNT-CO2 reactions, (4) applicability of ferrite-organometallic compounds in the CNT-CO2 synthesis reactions, and (5) the effects of process parameters such as temperature, etc.

Plasmid-Encoded Multidrug Resistance: A Case study of Salmonella and Shigella from enteric diarrhea sources among humans

Salmonellosis and shigellosis are significant and persistent causes of diarrheal diseases among humans in developing countries. With that in mind, the current study investigates the occurrence of plasmid-encoded multidrug resistances in Salmonella and Shigella from diarrheal cases among humans. The isolates were characterized by serotyping, antimicrobial-susceptibility testing, transfer experiments and curing. The extended spectrum β-lactamase (ESBL) was detected by the double disc diffusion synergy test (DDST). A significant number of the plasmid-encoded multidrug resistant (PEMDR) Salmonella and Shigella isolates were found to harbour transferable plasmid genes resistant to antibiotics like ampicillin, chloramphenicol, trimethoprim-sulfamethoxazole, ceftriaxone, cefuroxime and to a lesser extent to ciprofloxacin and ofloxacin. The conjugative R-plasmids-encoded extendedspectrum β-lactamase also showed resistances to cephalosporins (ceftriaxone and cefuroxime) and ampicillin. Curing experiments showed chromosomal resistances to varied antibiotics. The findings confirmed the presence of PEMDR in Salmonella and Shigella strains as a suitable adaptation to a changing antibiotic environment. The results therefore suggest the limited use of the commonly prescribed/or third generation cephalosporins as an empirical treatment of multidrug resistant Salmonella and Shigella because this may affect therapeutic outcomes.

Respondent-driven sampling as a recruitment method for men who have sex with men in southern sub-Saharan Africa: a cross-sectional analysis by wave

Objectives Respondent-driven sampling (RDS) is a popular method for recruiting men who have sex with men (MSM). Our objective is to describe the ability of RDS to reach MSM for HIV testing in three southern African nations. Methods Data collected via RDS among MSM in Lesotho (N=318), Swaziland (N=310) and Malawi (N=334) were analysed by wave in order to characterise differences in sample characteristics. Seeds were recruited from MSM-affiliated community-based organisations. Men were interviewed during a single study visit and tested for HIV. χ2 tests for trend were used to examine differences in the proportions across wave category. Results A maximum of 13–19 recruitment waves were achieved in each study site. The percentage of those who identified as gay/homosexual decreased as waves increased in Lesotho (49% to 27%, p<0.01). In Swaziland and Lesotho, knowledge that anal sex was the riskiest type of sex for HIV transmission decreased across waves (39% to 23%, p<0.05, and 37% to 19%, p<0.05). The percentage of participants who had ever received more than one HIV test decreased across waves in Malawi (31% to 12%, p<0.01). In Lesotho and Malawi, the prevalence of testing positive for HIV decreased across waves (48% to 15%, p<0.01 and 23% to 11%, p<0.05). Among those living with HIV, the proportion of those unaware of their status increased across waves in all study sites although this finding was not statistically significant. Conclusions RDS that extends deeper into recruitment waves may be a promising method of reaching MSM with varying levels of HIV prevention needs.

Sibanye Methods for Prevention Packages Program Project Protocol: Pilot Study of HIV Prevention Interventions for Men Who Have Sex With Men in South Africa

Background Human immunodeficiency virus (HIV) prevention intervention programs and related research for men who have sex with men (MSM) in the southern African region remain limited, despite the emergence of a severe epidemic among this group. With a lack of understanding of their social and sexual lives and HIV risks, and with MSM being a hidden and stigmatized group in the region, optimized HIV prevention packages for southern African MSM are an urgent public health and research priority. Objective The objective of the Sibanye Health Project is to develop and evaluate a combination package of biomedical, behavioral, and community-level HIV prevention interventions and services for MSM in South Africa. Methods The project consists of three phases: (1) a comprehensive literature review and summary of current HIV prevention interventions (Phase I), (2) agent-based mathematical modeling of HIV transmission in southern African MSM (Phase II), and (3) formative and stigma-related qualitative research, community engagement, training on providing health care to MSM, and the pilot study (Phase III). The pilot study is a prospective one-year study of 200 men in Cape Town and Port Elizabeth, South Africa. The study will assess a package of HIV prevention services, including condom and condom-compatible lubricant choices, risk-reduction counseling, couples HIV testing and counseling, pre-exposure prophylaxis (PrEP) for eligible men, and non-occupational post-exposure prophylaxis for men with a high risk exposure. The pilot study will begin in October 2014. Results Preliminary results from all components but the pilot study are available. We developed a literature review database with meta-data extracted from 3800 documents from 67 countries. Modeling results indicate that regular HIV testing and promotion of condom use can significantly impact new HIV infections among South African MSM, even in the context of high coverage of early treatment of HIV-positive men and high coverage of PrEP for at-risk HIV-negative men. Formative qualitative research consisted of 79 in-depth interviews, and six focus group discussions in Cape Town and Port Elizabeth. Analysis of these data has informed pilot study protocol development and has been documented in peer-reviewed manuscripts. Qualitative work regarding stigma faced by South African MSM resulted in finalized scales for use in the pilot study questionnaire. A total of 37 health care providers completed training designed to facilitate clinically and culturally competent care for MSM in the Eastern Cape. Conclusions The design of a future, larger study of the HIV prevention package will be conducted at the end of the pilot study, powered to detect efficacy of the prevention package. Data from the updated mathematical model, results of the pilot study, acceptability data, and advancements in HIV prevention sciences will be considered in developing the final proposed package and study design. Trial Registration ClinicalTrials.gov NCT02043015; http://clinicaltrials.gov/show/NCT02043015 (Archived by WebCite at http://www.webcitation.org/6THvp7rAj).

Impact of telemonitoring approaches on integrated HIV and TB diagnosis and treatment interventions in sub-Saharan Africa: a scoping review

Background: This paper explores telemonitoring/mhealth approaches as a promising real time and contextual strategy in overhauling HIV and TB interventions quality access and uptake, retention,adherence and coverage impact in endemic and prone-epidemic prevention and control in sub-Sahara Africa. Methods: The scoping review method was applied in acknowledged journals indexing platforms including Medline, Embase, Global Health, PubMed, MeSH PsycInfo, Scopus and Google Scholar to identify relevant articles pertaining to telemonitoring as a proxy surrogate method in reinforcing sustainability of HIV/TB prevention/treatment interventions in sub-Saharan Africa. Full papers were assessed and those selected that fosters evidence on telemonitoring/mhealth diagnosis, treatment approaches and strategies in HIV and TB prevention and control were synthesized and analyzed. Results: We found telemonitoring/mhealth approach as a more efficient and sustained proxy in HIV and TB risk reduction strategies for early diagnosis and prompt quality clinical outcomes. It can significantly contribute to decreasing health systems/patients cost, long waiting time in clinics, hospital visits, travels and time off/on from work. Improved integrated HIV and TB telemonitoring systems sustainability hold great promise in health systems strengthening including patient centered early diagnosis and care delivery systems, uptake and retention to medications/services and improving patients’ survival and quality of life. Conclusion: Telemonitoring/mhealth (electronic phone text/video/materials messaging)acceptability, access and uptake are crucial in monitoring and improving uptake, retention,adherence and coverage in both local and national integrated HIV and TB programs and interventions. Moreover, telemonitoring is crucial in patient-providers-health professional partnership, real-time quality care and service delivery, antiretroviral and anti-tuberculous drugs improvement, susceptibility monitoring and prescription choice, reinforcing cost effective HIV and TB integrated therapy model and survival rate.

Fostering prevention and care delivery services capability on HIV pandemic and Ebola outbreak symbiosis in Africa

Human immunodeficiency virus (HIV) and the re-emerging Ebola virus disease (EVD) are closely intertwined and remain a persistent public health threat and global challenge. Their origin and rapid transmission and spread have similar boundaries and share overlapping impact characteristics, including related symptoms and other interactions. The controversies and global threat of these viruses require rapid response policy and evidence-based implementation findings. The constraints and dual burden inflicted by Ebola and HIV infections are highly characterized by similar socio-demographics, socio-economic and political factors. EVD has similar effects and burdens to HIV infection. This study seeks to understand EVD in the context of HIV epidemic despite the challenges in developing an effective vaccine against HIV and EVD. Our findings show that early understanding, prevention and treatment of these diseases a global health threat mainly in Africa is important and valuable. The lessons learned so far from HIV and Ebola epidemics are crucial in health programming and execution of rapid response interventions and continued vigilance against EVD before it become another worldwide health menace. Therefore, the current regional West Africa EVD requires strengthening healthcare systems and building preparedness and response capacity. Importantly, appropriate community participation, health education and resilience coupled with deployment of effective novel diagnostic approaches in early warning and surveillance of threats and emerging diseases. Therefore, there is an urgent need to develop novel key strategies are crucial in curbing the constant viral resurgence, persistence transmission dynamics and spread, as well in accelerating Ebola vaccines regimen (immunization) development and national implementation plans in achieving sustained control, and eventual elimination.

The use of Carbon Nanotubes in Medical Applications - Is It a Success Story?

Since their rediscovery [1] by Iijima [2] carbon nanotubes (CNTs) have attracted a lot of interesting research due to their outstanding properties that have potential impact on broad areas of science and technology [3]. The name CNT originates from their nanometer-scale size. An ideal nanotube can be described as a network of carbon atoms assembled into a cylinder, which is covered at the end by half a fullerene molecule [4,5].

The response effect of pheochromocytoma (PC12) cell lines to oxidized multi-walled carbon nanotubes (o-MWCMTs)

BACKGROUND The applications of oxidized carbon nanotubes (o-CNTs) have shown potentials in novel drug delivery including the brain which is usually a challenge. This underscores the importance to study its potential toxic effect in animals. Despite being a promising tool for biomedical applications little is known about the safety of drugs in treating brain diseases. The toxicity of oxidized multi-walled carbon nanotubes (o-MWCNTs) are of utmost concern and in most in-vitro studies conducted so far are on dendritic cell (DC) lines with limited data on PC12 cell lines. OBJECTIVES We focused on the effect of o-MWCNTs in PC12 cells in vitro: a common model cell for neurotoxicity. METHODS The pristine multi-walled carbon nanotubes (p-MWCNTs) were produced by the swirled floating catalytic chemical vapour deposition method (SFCCVD). The p-MWCNTs were then oxidized using purified H2SO4/HNO3 (3:1v/v) and 30% HNO3 acids to produce o-MWCNTs. The Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM), Scanning electron microscopy (SEM), thermogravimetric analyser (TGA) and Raman spectroscopy techniques were used to characterize the MWCNTs. The PC12 cells were cultured in RPMI medium containing concentrations of o-MWCNTs ranging from 50 to 200 µg/ml. RESULTS The o-MWCNTs demonstrated slight cytotoxicity at short time period to PC12 neuronal cells whilst at longer time period, no significant (p > 0.05) toxicity was observed due to cell recovery. CONCLUSION In conclusion, the o-MWCNTs did not affect the growth rate and viability of the PC12 cells due to lack of considerable toxicity in the cells during the observed time period but further investigations are required to determine cell recovery mechanism.

Using Population-Size Estimation and Cross-sectional Survey Methods to Evaluate HIV Service Coverage Among Key Populations in Burkina Faso and Togo:

Objectives: The objective of our study was to measure progress toward the UNAIDS 90-90-90 HIV care targets among key populations in urban areas of 2 countries in West Africa: Burkina Faso and Togo. Methods: We recruited female sex workers (FSWs) and men who have sex with men (MSM) through respondent-driven sampling. From January to July 2013, 2738 participants were enrolled, tested for HIV, and completed interviewer-administered surveys. We used population-size estimation methods to calculate the number of people who were engaged in the HIV continuum of care. Results: HIV prevalence ranged from 0.6% (2 of 329) of MSM in Kara, Togo, to 32.9% (115 of 350) of FSWs in Bobo Dioulasso, Burkina Faso. Of those confirmed to be HIV infected, a range of 0.0% (0 of 2) of MSM in Kara to 55.7% (64 of 115) of FSWs in Bobo Dioulasso were using ART. Based on population estimates, the percentage gap between HIV-infected people who should be using ART (per the 90-90-90 targets) and those who reported using ART ranged from 31.5% among FSWs in Bobo Dioulasso to 100.0% among MSM in Kara. Conclusions: HIV service coverage among MSM and FSWs in Burkina Faso and Togo was low in 2013. Interventions for improving engagement of these at-risk populations in the HIV continuum of care should include frequent, routine HIV testing and linkage to evidence-based HIV treatment services. Population-size estimates can be used to inform governments, policy makers, and funding agencies about where elements of HIV service coverage are most needed.