Nanotech Viagra patch

Sildenafil citrate, commonly known as Viagra, is currently the first choice drug for erectile dysfunction but despite its success oral delivery of the drug is hampered by numerous side effects, the long delay before it starts working and the short amount of time it lasts. Researchers in Egypt think they may have a solution via nanotechnology.

Writing in the International Journal of Nanotechnology, the team describes tests on different formulations for sildenafil citrate transdermal nanocarriers as the delivery agent on human skin rather than the user having to swallow a pill. The benefits of such nanocarriers are that the drug gets into the bloodstream through the skin much more quickly than having to be ingested. Moreover, 70% of an oral dose of sildenafil citrate is wasted as it is metabolized by the liver without having any effect. Improved delivery via the transdermal route would avoid several side-effects as well as making onset of activity much quicker.

Pharmaceutical scientist Yosra S.R. Elnaggar of Alexandria University and professors there and at Alexandria and Pharos University, explain how previous attempts to create a Viagra transdermal application have been hampered by the properties of the drug itself. The drug has low oil and water solubility and is loathe to cross membranes, such as human skin, because of this. However, it is possible to encapsulate the drug in nanoemulsion based systems that can cross membranes readily. As such, the team has investigated two types of nanocarriers made using fat-like lipid molecules – the first made by forming an emulsion with the drug using a surfactant compound to allow the lipid molecules and drug to mix, much as soap will emulsify oil and water. The second option is a self-emulsifying nanocarrier that has its own inbuilt surfactant.

The team demonstrated in the laboratory that both formulations would have benefits for oral drug delivery, whereas only the nano-emulsion, rather than the self-emulsifying formulation, shows promise for a Viagra patch, in other words.

Elnaggar, Y., Massik, M., & Abdallah, O. (2011). Sildenafil citrate nanoemulsion vs. self-nanoemulsifying delivery systems: rational development and transdermal permeation International Journal of Nanotechnology, 8 (8/9) DOI: 10.1504/IJNT.2011.041443

Biofilters cut old landfill carbon footprint

Researchers in the US are testing biofilter systems as a viable alternative to releasing methane from passive landfill vents into the atmosphere. The technology could reduce the overall impact of old landfills on global warming. Details are reported in the current issue of the International Journal of Environmental Engineering.

Organic matter rotting in smaller, old landfill sites generates a slow trickle of the potent greenhouse gas, methane, into the atmosphere, amounting to just 2 or 3 kilograms per day per vent. In contrast to controlled methane generate for biofuel from modern, managed landfills, tapping this slow stream of the gas is not viable technologically or economically. However, methane has an infrared activity 21 times greater than carbon dioxide and so represents an important anthropogenic source of this greenhouse gas when attempting to balance the climate change books. Indeed, landfills contribute 12% of worldwide anthropogenic methane emissions due to the decomposition of organic waste.

Old landfills typically have passive gas vents. Methane is simply released into the atmosphere from these vents, or if the rate of emission is high enough it can be burned, or flared. According to Tarek Abichou and Jeffery Chanton of the Florida State University, Jose Morales of Environmental and Geotechnical Specialists, Inc., Tallahassee, Florida and Lei Yuan of Geosyntec Consultants in Columbia, Maryland, methane oxidation has recently been viewed as a more benign alternative to venting or flaring of landfill methane.

The researchers tested two biofilter designs capable of oxidizing methane gas to carbon dioxide and water. Both are packed with so-called methanotrophic bacteria, microbes that digest methane. They found that the radial biofilter design gave a much higher methane oxidation rate than a vertical biofilter. The higher surface area exposed to methane flow led to greater oxygen penetration into the biofilters, essential for microbial digestion. The radial biofilter has a surface area of well over 1.2 square meters whereas the vertical biofilter amounts to just 0.3 square meters area.

The team also found that the average percent oxidation rate of 20% and higher for the radial biofilter was possible when the air temperature was 20 to 36 Celsius, indicating the optimal soil temperature for methanotrophic bacteria to oxidize methane. Vertical biofilters averaged a little over 12% oxidation.

Abichou, T., Yuan, L., Chanton, J., & Morales, J. (2011). Mitigating methane emissions from passive landfill vents: a viable option for older closed landfills International Journal of Environmental Engineering, 3 (3/4) DOI: 10.1504/IJEE.2011.041354

The ignored virus that causes liver cancer

Hepatitis G virus was identified in 1995. Some little research was carried out on the virus and the US Food and Drug Administration (FDA) declared it a non-harmful virus in 1997. Researchers in Saudi Arabia, writing in the International Journal of Immunological Studies present evidence to suggest that this may have been the wrong decision. They claim that transmission of the virus through donated blood that was not screened for the virus as well as infection through other routes has led to an increase in cirrhosis of the liver and liver cancer.

Hepatitis G virus (HGV) was renamed as GB virus C (GBV-C) and is a virus in the Flaviviridae family but has not yet been assigned to a genus. Intriguingly, some evidence suggests that co-infection with the AIDS virus, HIV, somehow enhances the immune system in those patients. However, it is the effects of the virus on the livers of otherwise healthy patients that is of concern to Mughis Uddin Ahmed of the King Abdulaziz Hospital (NGHA) in Al-Ahsa, Saudi Arabia. He points out that since the FDA declared the virus not to cause health problems to humans in 1997, no donated blood has been screened for this virus.

However, Mughis Uddin Ahmed has carried out a review of the scientific literature for the last 16 years that show the virus to be quite prevalent around the globe. Moreover, there is a correlation with infection with this virus and hepatitis, cirrhosis of the liver and it is possibly linked to hepatocellular carcinoma. Mughis Uddin Ahmed also found an apparent link with hematological disorders and hematological malignancies.

For this reason, he suggests that research should be carried out into this virus to determine whether it is a true human pathogen and a viral carcinogen. He also advises that screening of donated blood for this virus should be reinstated urgently rather than healthcare workers continuing to transferring the virus ignorantly to blood recipients and risking the same morbidity and mortality outcomes seen with hepatitis C virus transferred from donor to recipient until screening for that virus was adopted.

Ahmed, Q. (2011). Hepatitis G virus (HGV): where we stand and what to do? International Journal of Immunological Studies, 1 (3) DOI: 10.1504/IJIS.2011.041723