Critical genetic link found between human taste differences and nicotine dependence

Could an aversion to bitter substances or an overall heightened sense of taste help protect some people from becoming addicted to nicotine? That's what researchers at UVA (University of Virginia) have found using an innovative new method they've developed to analyse the interactions of multiple genetic and environmental factors.

In a study published in the October 10, 2008 issue of The American Journal of Human Genetics, University of Virginia Health System researchers report that two interacting genes related to bitter taste sensitivity, TAS2R16 and TAS2R38, play an important role in a person's development of nicotine dependence and smoking behaviour. Researchers found that people with higher taste sensitivity aren't as likely to become dependant on nicotine as people with decreased taste sensitivity.

"This new knowledge is an important tool in predicting whether a person is likely to become a smoker or not," says lead investigator Ming Li, Ph.D., professor of psychiatry and behavioural neurosciences who specialises in addiction and genetics research.

It's long been known that a person's ability to taste bitter substances plays a crucial role in the rejection of potentially toxic foods, but taste sensitivity varies widely among individuals and between ethnic groups. Previous studies have suggested a link between so-called taster status and nicotine dependence, but genetic evidence underlying such a link has been lacking.

"Until now, the method for analysing gene to gene or gene to environment interactions could only handle one type of trait without correcting for other important covariants, such as age or gender, but we've developed a novel algorithm and corresponding computer program that can handle all types of genetic data and correct for any number of variants - gender, age, race, and so on," explains Dr. Li, who with his team studied genetic data of more than 2,000 participants from more than 600 families of African American or European American origin.

"We're laying an important foundation for addressing nicotine dependence. First we need to establish a comprehensive understanding of how all associated genes work together to affect smoking behaviours and addiction; that's what we're doing now. Once we have that base of knowledge, we can move on to develop effective prevention and treatment for nicotine dependence."

Source: Science Daily, 15 October 2008
Link: http://tinyurl.com/4dczy5

Study links nicotine with breast cancer growth and spread

A study published in Cancer Research, a journal of the American Association for Cancer Research, suggests a possible role for nicotine in breast tumour development and metastases. 

The study, conducted by researchers at the Beth Israel Deaconess Medical Center, is among the first to explore the effects of nicotine on mammary cells.

"Although numerous studies indicate the role of nicotine exposure in tumour promotion, little is known about the effect of nicotine on breast tumor development, especially on the metastatic process of breast cancer," said lead author Chang Yan Chen, Ph.D., M.D., at Beth Israel Deaconess Medical Center."

Through a series of in vitro tests Chen and her team of researchers determined that breast epithelial-like MCF10A cells and cancerous MCF7 cells both express several subunits of nAChR (nicotine receptor), that when bound, initiate a signaling process, potentially increasing cell growth and migration.

"The best known role of nAChR is in the nerve system," Chen said. "Although cells from various tissue origins express different subunits of nAChR, we know very little about the functions of nAChR in non-neuronal cells and tissues, in particular in mammary cells."

"We were able to determine that mammary cells express different subunits of nAChR and that nicotine, possibly through perturbing cell cycle checkpoints, potentiates tumorigenesis in mammary cancer-prone or cancer cells," Chen said.

Chen hopes to conduct more studies, in particular under the genetic backgrounds with loss or defect of different tumor suppressors, to further explore the effects of nicotine in relation to first- and secondhand exposure, on breast cancer initiation and development.

Source: Medical News Today, 14 October 2008
Link: http://tinyurl.com/4wd9j8

Smoking boosts women's risk of often-fatal aortic aneurysm: study

Researchers say that women who smoke have a dramatically higher risk of developing an abdominal aortic aneurysm than those who never used tobacco.

In a study published online by the British Medical Journal, researchers found that female smokers are four times more likely to have an aortic aneurysm rupture or need repair, compared to women who have quit smoking.

Furthermore, women who smoke have an eight-fold higher risk of rupture or the need for repair than those who never took up the habit, the study found. Previous research has shown that tobacco use also amplifies the prevalence of aortic aneurysms in men.

"Smoking is much more potent a factor on aortic aneurysm than it is in coronary artery disease or cerebral vascular disease," said lead author Dr. Frank Lederle, referring to the increased risk of heart attack and stroke due to smoking's contribution to diseased blood vessels.

"What we don't know is the method of causation," Lederle, an internist at Minnesota's VA Medical Center, said.

Although more common in men, abdominal aortic aneurysms are more deadly in women. Proportionally fewer women than men survive surgery to repair the artery.

"There are no symptoms until the aneurysm begins to rupture," Lederle said. "And that can be 10 years after it starts to form. So here's a disease that lies dormant for many years, easily detectable with ultrasound and yet frequently isn't detected and ultimately can be disastrous, because once rupture begins, 75 to 80 per cent of people who start to rupture will die."

"Half never get to an operating room and the operative mortality is over 50 per cent."

The research involved analyzing data from the U.S. Women's Health Initiative study, and looked at risk factors for rupture and repair of abdominal aortic aneurysms in almost 162,000 postmenopausal women, who were followed for an average of about eight years.

In an accompanying BMJ editorial, Prof. Janet Powell of Imperial College London and Prof. Paul Norman of the University of Western Australia said that the findings emphasise the need for educating women about quitting smoking to remain a public health priority.

They warn that if the incidence of abdominal aortic aneurysm in women continues to rise, then a population screening program for women who have smoked or continue to smoke may need to be implemented.

Source: The Canadian Press, 15 October 2008
Link: http://tinyurl.com/4m2ab4

Philippines: Smoking aggravates poverty

Smoking causes a lot of health complications that further aggravates the poor living conditions of disadvantaged families. 

This was emphasised by Secretary Esperanza I. Cabral of the Department of Social Welfare and Development (DSWD) during the Regional Forum on Tobacco Control and Sustainable Development.

The forum aims to strengthen links between public health advocates and economic and farming sectors, as well as to develop regional action plans to prioritise tobacco control as a way to help disadvantaged families alleviate poverty.

Secretary Cabral said the incidence of poverty can be traced to tobacco use based on a 2004 World Health Organization titled, "Tobacco and Poverty: A Vicious Cycle," which stated "that of the 1.3 billion smokers in the world, 84 percent live in developing countries, and that it is actually the poor who smoke the most; directly affecting the total household expenditurtes. Thus children and non-smoking family members are deprived of basic necessities such as food and healthcare so the smoking family member can sustain their tobacco addiction".

The DSWD report said that ten Filipinoss die of tobacco related diseases, every hour. Nearly 60 percent of all Filipino male adults smoke according to the Framework Convention Alliance on Tobaco Control. Smoking and Tobacco use, while often seen as a harmless habit by some smokers, push the poor even deeper into a vicious cycle of poverty."

Cabral noted that many families depend on tobacco as a means of livelihood. Thus, it is incumbent upon the government to develop substitute industries such as biofuels and high value crops in tobacco farming areas in order to provide tobacco farmers with better means of livelihood.

Source: PIA Daily News Reader, 16 October 2008
Link: http://tinyurl.com/4vdgot